Average Scroll Depth Metric: put scroll depth on the dashboard under a feature flag (#4832)

* migration: add scroll_depth to events_v2

* (cherry-pick) ingest scroll depth

* replace convoluted test with more concise ones

* QueryParser: parse internal scroll_depth metric + validation

* turn QueryComparisonsTest into QueryInternalTest

* rename file

* (cherry pick) query scroll depth 15b14d3

...and move the tests into `internal_query_test.exs`

* review feedback

* Get rid of unnecessary separation between aggregate and group scroll depth
* Drop irrelevant other metrics in tests

* add test ensuring scroll depth unavailable in Stats API v1

* Put scroll depth on the dashboard

* Top Stats
* Main Graph
* Top Pages > Details

* feature flag for dashboard scroll depth access

* ignore credo warning

* enable scroll_depth flag in tests

* remove duplication

* write timestamps explicitly in a test

* revert moving tests around

* Add query_comparisons_test back
* Move scroll_depth tests into query_test
* Delete query_internal_test

* rename setup util (got updated on master)

* use pageleave_factory where applicable

* Use the correct generated query-api.d.ts

* npm format

assets/js/dashboard/stats/graph/graph-util.js

@@ -15,7 +15,8 @@ export function getGraphableMetrics(query, site) {
   } else if (isGoalFilter) {
     return ["visitors", "events", "conversion_rate"]
   } else if (isPageFilter) {
-    return ["visitors", "visits", "pageviews", "bounce_rate"]
+    const pageFilterMetrics = ["visitors", "visits", "pageviews", "bounce_rate"]
+    return site.flags.scroll_depth ? [...pageFilterMetrics, "scroll_depth"] : pageFilterMetrics
   } else {
     return ["visitors", "visits", "pageviews", "views_per_visit", "bounce_rate", "visit_duration"]
   }

assets/js/dashboard/stats/modals/pages.js

@@ -47,12 +47,14 @@ function PagesModal() {
       ]
     }
     
-    return [
+    const defaultMetrics = [
       metrics.createVisitors({renderLabel: (_query) => "Visitors" }),
       metrics.createPageviews(),
       metrics.createBounceRate(),
       metrics.createTimeOnPage()
     ]
+    
+    return site.flags.scroll_depth ? [...defaultMetrics, metrics.createScrollDepth()] : defaultMetrics
   }
 
   return (

assets/js/dashboard/stats/reports/metric-formatter.ts

@@ -38,6 +38,7 @@ export const MetricFormatterShort: Record<
 
   bounce_rate: percentageFormatter,
   conversion_rate: percentageFormatter,
+  scroll_depth: percentageFormatter,
   exit_rate: percentageFormatter,
   group_conversion_rate: percentageFormatter,
   percentage: percentageFormatter,
@@ -65,6 +66,7 @@ export const MetricFormatterLong: Record<
 
   bounce_rate: percentageFormatter,
   conversion_rate: percentageFormatter,
+  scroll_depth: percentageFormatter,
   exit_rate: percentageFormatter,
   group_conversion_rate: percentageFormatter,
   percentage: percentageFormatter,

assets/js/dashboard/stats/reports/metrics.js

@@ -172,7 +172,7 @@ export const createVisitDuration = (props) => {
 export const createBounceRate = (props) => {
   const renderLabel = (_query) => 'Bounce Rate'
   return new Metric({
-    width: 'w-32',
+    width: 'w-28',
     ...props,
     key: 'bounce_rate',
     renderLabel,
@@ -194,7 +194,7 @@ export const createPageviews = (props) => {
 export const createTimeOnPage = (props) => {
   const renderLabel = (_query) => 'Time on Page'
   return new Metric({
-    width: 'w-32',
+    width: 'w-28',
     ...props,
     key: 'time_on_page',
     renderLabel,
@@ -212,3 +212,14 @@ export const createExitRate = (props) => {
     sortable: false
   })
 }
+
+export const createScrollDepth = (props) => {
+  const renderLabel = (_query) => 'Scroll Depth'
+  return new Metric({
+    width: 'w-28',
+    ...props,
+    key: 'scroll_depth',
+    renderLabel,
+    sortable: false
+  })
+}

assets/js/types/query-api.d.ts

@@ -18,7 +18,8 @@ export type Metric =
   | "group_conversion_rate"
   | "time_on_page"
   | "total_revenue"
-  | "average_revenue";
+  | "average_revenue"
+  | "scroll_depth";
 export type DateRangeShorthand = "30m" | "realtime" | "all" | "day" | "7d" | "30d" | "month" | "6mo" | "12mo" | "year";
 /**
  * @minItems 2

lib/plausible/stats/filters/query_parser.ex

@@ -541,6 +541,17 @@ defmodule Plausible.Stats.Filters.QueryParser do
     end
   end
 
+  defp validate_metric(:scroll_depth = metric, query) do
+    page_dimension? = Enum.member?(query.dimensions, "event:page")
+    toplevel_page_filter? = not is_nil(Filters.get_toplevel_filter(query, "event:page"))
+
+    if page_dimension? or toplevel_page_filter? do
+      :ok
+    else
+      {:error, "Metric `#{metric}` can only be queried with event:page filters or dimensions."}
+    end
+  end
+
   defp validate_metric(:views_per_visit = metric, query) do
     cond do
       Filters.filtering_on_dimension?(query, "event:page") ->

lib/plausible/stats/metrics.ex

@@ -18,7 +18,8 @@ defmodule Plausible.Stats.Metrics do
                  :conversion_rate,
                  :group_conversion_rate,
                  :time_on_page,
-                 :percentage
+                 :percentage,
+                 :scroll_depth
                ] ++ on_ee(do: Plausible.Stats.Goal.Revenue.revenue_metrics(), else: [])
 
   @metric_mappings Enum.into(@all_metrics, %{}, fn metric -> {to_string(metric), metric} end)

lib/plausible/stats/sql/expression.ex

@@ -245,6 +245,7 @@ defmodule Plausible.Stats.SQL.Expression do
 
   def event_metric(:percentage), do: %{}
   def event_metric(:conversion_rate), do: %{}
+  def event_metric(:scroll_depth), do: %{}
   def event_metric(:group_conversion_rate), do: %{}
   def event_metric(:total_visitors), do: %{}
 

lib/plausible/stats/sql/query_builder.ex

@@ -126,7 +126,7 @@ defmodule Plausible.Stats.SQL.QueryBuilder do
     |> Enum.reduce(%{}, &Map.merge/2)
   end
 
-  defp build_group_by(q, table, query) do
+  def build_group_by(q, table, query) do
     Enum.reduce(query.dimensions, q, &dimension_group_by(&2, table, query, &1))
   end
 

lib/plausible/stats/sql/special_metrics.ex

@@ -16,6 +16,7 @@ defmodule Plausible.Stats.SQL.SpecialMetrics do
     |> maybe_add_percentage_metric(site, query)
     |> maybe_add_global_conversion_rate(site, query)
     |> maybe_add_group_conversion_rate(site, query)
+    |> maybe_add_scroll_depth(site, query)
   end
 
   defp maybe_add_percentage_metric(q, site, query) do
@@ -121,6 +122,55 @@ defmodule Plausible.Stats.SQL.SpecialMetrics do
     end
   end
 
+  def maybe_add_scroll_depth(q, site, query) do
+    if :scroll_depth in query.metrics do
+      max_per_visitor_q =
+        Base.base_event_query(site, query)
+        |> where([e], e.name == "pageleave")
+        |> select([e], %{
+          user_id: e.user_id,
+          max_scroll_depth: max(e.scroll_depth)
+        })
+        |> SQL.QueryBuilder.build_group_by(:events, query)
+        |> group_by([e], e.user_id)
+
+      dim_shortnames = Enum.map(query.dimensions, fn dim -> shortname(query, dim) end)
+
+      dim_select =
+        dim_shortnames
+        |> Enum.map(fn dim -> {dim, dynamic([p], field(p, ^dim))} end)
+        |> Map.new()
+
+      dim_group_by =
+        dim_shortnames
+        |> Enum.map(fn dim -> dynamic([p], field(p, ^dim)) end)
+
+      scroll_depth_q =
+        subquery(max_per_visitor_q)
+        |> select([p], %{
+          scroll_depth: fragment("toUInt8(round(ifNotFinite(avg(?), 0)))", p.max_scroll_depth)
+        })
+        |> select_merge(^dim_select)
+        |> group_by(^dim_group_by)
+
+      join_on_dim_condition =
+        if dim_shortnames == [] do
+          true
+        else
+          dim_shortnames
+          |> Enum.map(fn dim -> dynamic([_e, ..., s], selected_as(^dim) == field(s, ^dim)) end)
+          # credo:disable-for-next-line Credo.Check.Refactor.Nesting
+          |> Enum.reduce(fn condition, acc -> dynamic([], ^acc and ^condition) end)
+        end
+
+      q
+      |> join(:left, [e], s in subquery(scroll_depth_q), on: ^join_on_dim_condition)
+      |> select_merge_as([_e, ..., s], %{scroll_depth: fragment("any(?)", s.scroll_depth)})
+    else
+      q
+    end
+  end
+
   # `total_visitors_subquery` returns a subquery which selects `total_visitors` -
   # the number used as the denominator in the calculation of `conversion_rate` and
   # `percentage` metrics.

lib/plausible/stats/table_decider.ex

@@ -74,6 +74,7 @@ defmodule Plausible.Stats.TableDecider do
 
   defp metric_partitioner(_, :average_revenue), do: :event
   defp metric_partitioner(_, :total_revenue), do: :event
+  defp metric_partitioner(_, :scroll_depth), do: :event
   defp metric_partitioner(_, :pageviews), do: :event
   defp metric_partitioner(_, :events), do: :event
   defp metric_partitioner(_, :bounce_rate), do: :session

lib/plausible/stats/timeseries.ex

@@ -87,6 +87,7 @@ defmodule Plausible.Stats.Timeseries do
         :views_per_visit -> Map.merge(row, %{views_per_visit: 0.0})
         :conversion_rate -> Map.merge(row, %{conversion_rate: 0.0})
         :group_conversion_rate -> Map.merge(row, %{group_conversion_rate: 0.0})
+        :scroll_depth -> Map.merge(row, %{scroll_depth: 0})
         :bounce_rate -> Map.merge(row, %{bounce_rate: 0.0})
         :visit_duration -> Map.merge(row, %{visit_duration: nil})
         :average_revenue -> Map.merge(row, %{average_revenue: nil})

lib/plausible_web/controllers/api/stats_controller.ex

@@ -193,12 +193,13 @@ defmodule PlausibleWeb.Api.StatsController do
 
   def top_stats(conn, params) do
     site = conn.assigns[:site]
+    current_user = conn.assigns[:current_user]
 
     params = realtime_period_to_30m(params)
 
     query = Query.from(site, params, debug_metadata(conn))
 
-    {top_stats, sample_percent} = fetch_top_stats(site, query)
+    {top_stats, sample_percent} = fetch_top_stats(site, query, current_user)
     comparison_query = comparison_query(query)
 
     json(conn, %{
@@ -293,7 +294,7 @@ defmodule PlausibleWeb.Api.StatsController do
     end
   end
 
-  defp fetch_top_stats(site, query) do
+  defp fetch_top_stats(site, query, current_user) do
     goal_filter? = Filters.filtering_on_dimension?(query, "event:goal")
 
     cond do
@@ -307,7 +308,7 @@ defmodule PlausibleWeb.Api.StatsController do
         fetch_goal_top_stats(site, query)
 
       true ->
-        fetch_other_top_stats(site, query)
+        fetch_other_top_stats(site, query, current_user)
     end
   end
 
@@ -391,16 +392,24 @@ defmodule PlausibleWeb.Api.StatsController do
     |> then(&{&1, 100})
   end
 
-  defp fetch_other_top_stats(site, query) do
+  defp fetch_other_top_stats(site, query, current_user) do
     page_filter? = Filters.filtering_on_dimension?(query, "event:page")
 
     metrics = [:visitors, :visits, :pageviews, :sample_percent]
 
     metrics =
       cond do
-        page_filter? && query.include_imported -> metrics
+        page_filter? && query.include_imported ->
-        page_filter? -> metrics ++ [:bounce_rate, :time_on_page]
+          metrics
-        true -> metrics ++ [:views_per_visit, :bounce_rate, :visit_duration]
+
+        page_filter? && scroll_depth_enabled?(site, current_user) ->
+          metrics ++ [:bounce_rate, :scroll_depth, :time_on_page]
+
+        page_filter? ->
+          metrics ++ [:bounce_rate, :time_on_page]
+
+        true ->
+          metrics ++ [:views_per_visit, :bounce_rate, :visit_duration]
       end
 
     current_results = Stats.aggregate(site, query, metrics)
@@ -418,7 +427,8 @@ defmodule PlausibleWeb.Api.StatsController do
             nil -> 0
             value -> value
           end
-        )
+        ),
+        top_stats_entry(current_results, "Scroll depth", :scroll_depth)
       ]
       |> Enum.filter(& &1)
 
@@ -819,13 +829,22 @@ defmodule PlausibleWeb.Api.StatsController do
 
   def pages(conn, params) do
     site = conn.assigns[:site]
+    current_user = conn.assigns[:current_user]
+
     params = Map.put(params, "property", "event:page")
     query = Query.from(site, params, debug_metadata(conn))
 
     extra_metrics =
-      if params["detailed"],
+      cond do
-        do: [:pageviews, :bounce_rate, :time_on_page],
+        params["detailed"] && !query.include_imported && scroll_depth_enabled?(site, current_user) ->
-        else: []
+          [:pageviews, :bounce_rate, :time_on_page, :scroll_depth]
+
+        params["detailed"] ->
+          [:pageviews, :bounce_rate, :time_on_page]
+
+        true ->
+          []
+      end
 
     metrics = breakdown_metrics(query, extra_metrics)
     pagination = parse_pagination(params)
@@ -1532,11 +1551,20 @@ defmodule PlausibleWeb.Api.StatsController do
       end
 
     requires_goal_filter? = metric in [:conversion_rate, :events]
+    has_goal_filter? = Filters.filtering_on_dimension?(query, "event:goal")
 
-    if requires_goal_filter? and !Filters.filtering_on_dimension?(query, "event:goal") do
+    requires_page_filter? = metric == :scroll_depth
-      {:error, "Metric `#{metric}` can only be queried with a goal filter"}
+    has_page_filter? = Filters.filtering_on_dimension?(query, "event:page")
-    else
+
-      {:ok, metric}
+    cond do
+      requires_goal_filter? and not has_goal_filter? ->
+        {:error, "Metric `#{metric}` can only be queried with a goal filter"}
+
+      requires_page_filter? and not has_page_filter? ->
+        {:error, "Metric `#{metric}` can only be queried with a page filter"}
+
+      true ->
+        {:ok, metric}
     end
   end
 
@@ -1588,4 +1616,9 @@ defmodule PlausibleWeb.Api.StatsController do
   end
 
   defp realtime_period_to_30m(params), do: params
+
+  defp scroll_depth_enabled?(site, user) do
+    FunWithFlags.enabled?(:scroll_depth, for: user) ||
+      FunWithFlags.enabled?(:scroll_depth, for: site)
+  end
 end

lib/plausible_web/controllers/stats_controller.ex

@@ -375,7 +375,7 @@ defmodule PlausibleWeb.StatsController do
 
   defp get_flags(user, site),
     do:
-      [:channels, :saved_segments]
+      [:channels, :saved_segments, :scroll_depth]
       |> Enum.map(fn flag ->
         {flag, FunWithFlags.enabled?(flag, for: user) || FunWithFlags.enabled?(flag, for: site)}
       end)

priv/json-schemas/query-api-schema.json

@@ -269,6 +269,10 @@
         {
           "const": "average_revenue",
           "$comment": "only :internal"
+        },
+        {
+          "const": "scroll_depth",
+          "$comment": "only :internal"
         }
       ]
     },

test/plausible/billing/quota_test.exs

@@ -721,7 +721,7 @@ defmodule Plausible.Billing.QuotaTest do
       populate_stats(site, [
         build(:event, timestamp: Timex.shift(now, days: -8), name: "custom"),
         build(:pageview, user_id: 199, timestamp: Timex.shift(now, days: -5, minutes: -2)),
-        build(:event, user_id: 199, timestamp: Timex.shift(now, days: -5), name: "pageleave")
+        build(:pageleave, user_id: 199, timestamp: Timex.shift(now, days: -5))
       ])
 
       assert %{

test/plausible/stats/goal_suggestions_test.exs

@@ -63,7 +63,7 @@ defmodule Plausible.Stats.GoalSuggestionsTest do
           user_id: 1,
           timestamp: NaiveDateTime.utc_now() |> NaiveDateTime.add(-1, :minute)
         ),
-        build(:event, name: "pageleave", user_id: 1, timestamp: NaiveDateTime.utc_now())
+        build(:pageleave, user_id: 1, timestamp: NaiveDateTime.utc_now())
       ])
 
       assert GoalSuggestions.suggest_event_names(site, "") == ["Signup"]

test/plausible/stats/query_parser_test.exs

@@ -1416,6 +1416,81 @@ defmodule Plausible.Stats.Filters.QueryParserTest do
     end
   end
 
+  describe "scroll_depth metric" do
+    test "fails validation on its own", %{site: site} do
+      %{
+        "site_id" => site.domain,
+        "metrics" => ["scroll_depth"],
+        "date_range" => "all"
+      }
+      |> check_error(
+        site,
+        "Metric `scroll_depth` can only be queried with event:page filters or dimensions.",
+        :internal
+      )
+    end
+
+    test "fails with only a non-top-level event:page filter", %{site: site} do
+      %{
+        "site_id" => site.domain,
+        "metrics" => ["scroll_depth"],
+        "date_range" => "all",
+        "filters" => [["not", ["is", "event:page", ["/"]]]]
+      }
+      |> check_error(
+        site,
+        "Metric `scroll_depth` can only be queried with event:page filters or dimensions.",
+        :internal
+      )
+    end
+
+    test "succeeds with top-level event:page filter", %{site: site} do
+      %{
+        "site_id" => site.domain,
+        "metrics" => ["scroll_depth"],
+        "date_range" => "all",
+        "filters" => [["is", "event:page", ["/"]]]
+      }
+      |> check_success(
+        site,
+        %{
+          metrics: [:scroll_depth],
+          utc_time_range: @date_range_day,
+          filters: [[:is, "event:page", ["/"]]],
+          dimensions: [],
+          order_by: nil,
+          timezone: site.timezone,
+          include: %{imports: false, time_labels: false, total_rows: false, comparisons: nil},
+          pagination: %{limit: 10_000, offset: 0}
+        },
+        :internal
+      )
+    end
+
+    test "succeeds with event:page dimension", %{site: site} do
+      %{
+        "site_id" => site.domain,
+        "metrics" => ["scroll_depth"],
+        "date_range" => "all",
+        "dimensions" => ["event:page"]
+      }
+      |> check_success(
+        site,
+        %{
+          metrics: [:scroll_depth],
+          utc_time_range: @date_range_day,
+          filters: [],
+          dimensions: ["event:page"],
+          order_by: nil,
+          timezone: site.timezone,
+          include: %{imports: false, time_labels: false, total_rows: false, comparisons: nil},
+          pagination: %{limit: 10_000, offset: 0}
+        },
+        :internal
+      )
+    end
+  end
+
   describe "views_per_visit metric" do
     test "succeeds with normal filters", %{site: site} do
       insert(:goal, %{site: site, event_name: "Signup"})

test/plausible_web/controllers/api/external_stats_controller/aggregate_test.exs

@@ -126,6 +126,20 @@ defmodule PlausibleWeb.Api.ExternalStatsController.AggregateTest do
              }
     end
 
+    test "scroll depth metric is not recognized in the legacy API v1", %{conn: conn, site: site} do
+      conn =
+        get(conn, "/api/v1/stats/aggregate", %{
+          "site_id" => site.domain,
+          "period" => "30d",
+          "metrics" => "scroll_depth"
+        })
+
+      assert json_response(conn, 400) == %{
+               "error" =>
+                 "The metric `scroll_depth` is not recognized. Find valid metrics from the documentation: https://plausible.io/docs/stats-api#metrics"
+             }
+    end
+
     for property <- ["event:name", "event:goal", "event:props:custom_prop"] do
       test "validates that session metrics cannot be used with #{property} filter", %{
         conn: conn,
@@ -1628,12 +1642,7 @@ defmodule PlausibleWeb.Api.ExternalStatsController.AggregateTest do
       populate_stats(site, [
         build(:pageview, user_id: 1234, timestamp: ~N[2021-01-01 12:00:00], pathname: "/1"),
         build(:pageview, user_id: 1234, timestamp: ~N[2021-01-01 12:00:05], pathname: "/2"),
-        build(:event,
+        build(:pageleave, user_id: 1234, timestamp: ~N[2021-01-01 12:01:00], pathname: "/1")
-          name: "pageleave",
-          user_id: 1234,
-          timestamp: ~N[2021-01-01 12:01:00],
-          pathname: "/1"
-        )
       ])
 
       conn =

test/plausible_web/controllers/api/external_stats_controller/breakdown_test.exs

@@ -2604,12 +2604,7 @@ defmodule PlausibleWeb.Api.ExternalStatsController.BreakdownTest do
       populate_stats(site, [
         build(:pageview, user_id: 1234, timestamp: ~N[2021-01-01 12:00:00], pathname: "/1"),
         build(:pageview, user_id: 1234, timestamp: ~N[2021-01-01 12:00:05], pathname: "/2"),
-        build(:event,
+        build(:pageleave, user_id: 1234, timestamp: ~N[2021-01-01 12:01:00], pathname: "/1")
-          name: "pageleave",
-          user_id: 1234,
-          timestamp: ~N[2021-01-01 12:01:00],
-          pathname: "/1"
-        )
       ])
 
       conn =

test/plausible_web/controllers/api/external_stats_controller/query_test.exs

@@ -105,7 +105,7 @@ defmodule PlausibleWeb.Api.ExternalStatsController.QueryTest do
          %{conn: conn, site: site} do
       populate_stats(site, [
         build(:pageview, user_id: 234, timestamp: ~N[2021-01-01 00:00:00]),
-        build(:event, user_id: 234, name: "pageleave", timestamp: ~N[2021-01-01 00:00:01])
+        build(:pageleave, user_id: 234, timestamp: ~N[2021-01-01 00:00:01])
       ])
 
       conn =
@@ -126,7 +126,7 @@ defmodule PlausibleWeb.Api.ExternalStatsController.QueryTest do
     } do
       populate_stats(site, [
         build(:pageview, user_id: 123, timestamp: ~N[2021-01-01 00:00:00]),
-        build(:event, user_id: 123, name: "pageleave", timestamp: ~N[2021-01-01 00:00:03])
+        build(:pageleave, user_id: 123, timestamp: ~N[2021-01-01 00:00:03])
       ])
 
       conn =
@@ -3426,4 +3426,298 @@ defmodule PlausibleWeb.Api.ExternalStatsController.QueryTest do
       assert json_response(conn4, 200)["results"] == []
     end
   end
+
+  describe "scroll_depth" do
+    setup [:create_user, :create_site, :create_api_key, :use_api_key]
+
+    test "scroll depth is (not yet) available in public API", %{conn: conn, site: site} do
+      conn =
+        post(conn, "/api/v2/query", %{
+          "site_id" => site.domain,
+          "filters" => [["is", "event:page", ["/"]]],
+          "date_range" => "all",
+          "metrics" => ["scroll_depth"]
+        })
+
+      assert json_response(conn, 400)["error"] =~ "Invalid metric \"scroll_depth\""
+    end
+
+    test "can query scroll_depth metric with a page filter", %{conn: conn, site: site} do
+      populate_stats(site, [
+        build(:pageview, user_id: 123, timestamp: ~N[2021-01-01 00:00:00]),
+        build(:pageleave, user_id: 123, timestamp: ~N[2021-01-01 00:00:10], scroll_depth: 40),
+        build(:pageview, user_id: 123, timestamp: ~N[2021-01-01 00:00:10]),
+        build(:pageleave, user_id: 123, timestamp: ~N[2021-01-01 00:00:20], scroll_depth: 60),
+        build(:pageview, user_id: 456, timestamp: ~N[2021-01-01 00:00:00]),
+        build(:pageleave, user_id: 456, timestamp: ~N[2021-01-01 00:00:10], scroll_depth: 80)
+      ])
+
+      conn =
+        post(conn, "/api/v2/query-internal-test", %{
+          "site_id" => site.domain,
+          "filters" => [["is", "event:page", ["/"]]],
+          "date_range" => "all",
+          "metrics" => ["scroll_depth"]
+        })
+
+      assert json_response(conn, 200)["results"] == [
+               %{"metrics" => [70], "dimensions" => []}
+             ]
+    end
+
+    test "scroll depth is 0 when no pageleave data in range", %{conn: conn, site: site} do
+      populate_stats(site, [
+        build(:pageview, timestamp: ~N[2021-01-01 00:00:00])
+      ])
+
+      conn =
+        post(conn, "/api/v2/query-internal-test", %{
+          "site_id" => site.domain,
+          "filters" => [["is", "event:page", ["/"]]],
+          "date_range" => "all",
+          "metrics" => ["visitors", "scroll_depth"]
+        })
+
+      assert json_response(conn, 200)["results"] == [
+               %{"metrics" => [1, 0], "dimensions" => []}
+             ]
+    end
+
+    test "scroll depth is 0 when no data at all in range", %{conn: conn, site: site} do
+      conn =
+        post(conn, "/api/v2/query-internal-test", %{
+          "site_id" => site.domain,
+          "filters" => [["is", "event:page", ["/"]]],
+          "date_range" => "all",
+          "metrics" => ["scroll_depth"]
+        })
+
+      assert json_response(conn, 200)["results"] == [
+               %{"metrics" => [0], "dimensions" => []}
+             ]
+    end
+
+    test "scroll_depth metric in a time:day breakdown", %{conn: conn, site: site} do
+      t0 = ~N[2020-01-01 00:00:00]
+      [t1, t2, t3] = for i <- 1..3, do: NaiveDateTime.add(t0, i, :minute)
+
+      populate_stats(site, [
+        build(:pageview, user_id: 12, timestamp: t0),
+        build(:pageleave, user_id: 12, timestamp: t1, scroll_depth: 20),
+        build(:pageview, user_id: 34, timestamp: t0),
+        build(:pageleave, user_id: 34, timestamp: t1, scroll_depth: 17),
+        build(:pageview, user_id: 34, timestamp: t2),
+        build(:pageleave, user_id: 34, timestamp: t3, scroll_depth: 60),
+        build(:pageview, user_id: 56, timestamp: NaiveDateTime.add(t0, 1, :day)),
+        build(:pageleave,
+          user_id: 56,
+          timestamp: NaiveDateTime.add(t1, 1, :day),
+          scroll_depth: 20
+        )
+      ])
+
+      conn =
+        post(conn, "/api/v2/query-internal-test", %{
+          "site_id" => site.domain,
+          "metrics" => ["scroll_depth"],
+          "date_range" => "all",
+          "dimensions" => ["time:day"],
+          "filters" => [["is", "event:page", ["/"]]]
+        })
+
+      assert json_response(conn, 200)["results"] == [
+               %{"dimensions" => ["2020-01-01"], "metrics" => [40]},
+               %{"dimensions" => ["2020-01-02"], "metrics" => [20]}
+             ]
+    end
+
+    test "breakdown by event:page with scroll_depth metric", %{conn: conn, site: site} do
+      t0 = ~N[2020-01-01 00:00:00]
+      [t1, t2, t3] = for i <- 1..3, do: NaiveDateTime.add(t0, i, :minute)
+
+      populate_stats(site, [
+        build(:pageview, user_id: 12, pathname: "/blog", timestamp: t0),
+        build(:pageleave, user_id: 12, pathname: "/blog", timestamp: t1, scroll_depth: 20),
+        build(:pageview, user_id: 12, pathname: "/another", timestamp: t1),
+        build(:pageleave, user_id: 12, pathname: "/another", timestamp: t2, scroll_depth: 24),
+        build(:pageview, user_id: 34, pathname: "/blog", timestamp: t0),
+        build(:pageleave, user_id: 34, pathname: "/blog", timestamp: t1, scroll_depth: 17),
+        build(:pageview, user_id: 34, pathname: "/another", timestamp: t1),
+        build(:pageleave, user_id: 34, pathname: "/another", timestamp: t2, scroll_depth: 26),
+        build(:pageview, user_id: 34, pathname: "/blog", timestamp: t2),
+        build(:pageleave, user_id: 34, pathname: "/blog", timestamp: t3, scroll_depth: 60),
+        build(:pageview, user_id: 56, pathname: "/blog", timestamp: t0),
+        build(:pageleave, user_id: 56, pathname: "/blog", timestamp: t1, scroll_depth: 100)
+      ])
+
+      conn =
+        post(conn, "/api/v2/query-internal-test", %{
+          "site_id" => site.domain,
+          "metrics" => ["scroll_depth"],
+          "date_range" => "all",
+          "dimensions" => ["event:page"]
+        })
+
+      assert json_response(conn, 200)["results"] == [
+               %{"dimensions" => ["/blog"], "metrics" => [60]},
+               %{"dimensions" => ["/another"], "metrics" => [25]}
+             ]
+    end
+
+    test "breakdown by event:page + visit:source with scroll_depth metric", %{
+      conn: conn,
+      site: site
+    } do
+      populate_stats(site, [
+        build(:pageview,
+          referrer_source: "Google",
+          user_id: 12,
+          pathname: "/blog",
+          timestamp: ~N[2020-01-01 00:00:00]
+        ),
+        build(:pageleave,
+          referrer_source: "Google",
+          user_id: 12,
+          pathname: "/blog",
+          timestamp: ~N[2020-01-01 00:00:00] |> NaiveDateTime.add(1, :minute),
+          scroll_depth: 20
+        ),
+        build(:pageview,
+          referrer_source: "Google",
+          user_id: 34,
+          pathname: "/blog",
+          timestamp: ~N[2020-01-01 00:00:00]
+        ),
+        build(:pageleave,
+          referrer_source: "Google",
+          user_id: 34,
+          pathname: "/blog",
+          timestamp: ~N[2020-01-01 00:00:00] |> NaiveDateTime.add(1, :minute),
+          scroll_depth: 17
+        ),
+        build(:pageview,
+          referrer_source: "Google",
+          user_id: 34,
+          pathname: "/blog",
+          timestamp: ~N[2020-01-01 00:00:00] |> NaiveDateTime.add(2, :minute)
+        ),
+        build(:pageleave,
+          referrer_source: "Google",
+          user_id: 34,
+          pathname: "/blog",
+          timestamp: ~N[2020-01-01 00:00:00] |> NaiveDateTime.add(3, :minute),
+          scroll_depth: 60
+        ),
+        build(:pageview,
+          referrer_source: "Twitter",
+          user_id: 56,
+          pathname: "/blog",
+          timestamp: ~N[2020-01-01 00:00:00]
+        ),
+        build(:pageleave,
+          referrer_source: "Twitter",
+          user_id: 56,
+          pathname: "/blog",
+          timestamp: ~N[2020-01-01 00:00:00] |> NaiveDateTime.add(1, :minute),
+          scroll_depth: 20
+        ),
+        build(:pageview,
+          referrer_source: "Twitter",
+          user_id: 56,
+          pathname: "/another",
+          timestamp: ~N[2020-01-01 00:00:00] |> NaiveDateTime.add(1, :minute)
+        ),
+        build(:pageleave,
+          referrer_source: "Twitter",
+          user_id: 56,
+          pathname: "/another",
+          timestamp: ~N[2020-01-01 00:00:00] |> NaiveDateTime.add(2, :minute),
+          scroll_depth: 24
+        )
+      ])
+
+      conn =
+        post(conn, "/api/v2/query-internal-test", %{
+          "site_id" => site.domain,
+          "metrics" => ["scroll_depth"],
+          "date_range" => "all",
+          "dimensions" => ["event:page", "visit:source"]
+        })
+
+      assert json_response(conn, 200)["results"] == [
+               %{"dimensions" => ["/blog", "Google"], "metrics" => [40]},
+               %{"dimensions" => ["/another", "Twitter"], "metrics" => [24]},
+               %{"dimensions" => ["/blog", "Twitter"], "metrics" => [20]}
+             ]
+    end
+
+    test "breakdown by event:page + time:day with scroll_depth metric", %{conn: conn, site: site} do
+      populate_stats(site, [
+        build(:pageview, user_id: 12, pathname: "/blog", timestamp: ~N[2020-01-01 00:00:00]),
+        build(:pageleave,
+          user_id: 12,
+          pathname: "/blog",
+          timestamp: ~N[2020-01-01 00:01:00],
+          scroll_depth: 20
+        ),
+        build(:pageview, user_id: 12, pathname: "/another", timestamp: ~N[2020-01-01 00:01:00]),
+        build(:pageleave,
+          user_id: 12,
+          pathname: "/another",
+          timestamp: ~N[2020-01-01 00:02:00],
+          scroll_depth: 24
+        ),
+        build(:pageview, user_id: 34, pathname: "/blog", timestamp: ~N[2020-01-01 00:00:00]),
+        build(:pageleave,
+          user_id: 34,
+          pathname: "/blog",
+          timestamp: ~N[2020-01-01 00:01:00],
+          scroll_depth: 17
+        ),
+        build(:pageview, user_id: 34, pathname: "/another", timestamp: ~N[2020-01-01 00:01:00]),
+        build(:pageleave,
+          user_id: 34,
+          pathname: "/another",
+          timestamp: ~N[2020-01-01 00:02:00],
+          scroll_depth: 26
+        ),
+        build(:pageview, user_id: 34, pathname: "/blog", timestamp: ~N[2020-01-01 00:02:00]),
+        build(:pageleave,
+          user_id: 34,
+          pathname: "/blog",
+          timestamp: ~N[2020-01-01 00:03:00],
+          scroll_depth: 60
+        ),
+        build(:pageview, user_id: 56, pathname: "/blog", timestamp: ~N[2020-01-02 00:00:00]),
+        build(:pageleave,
+          user_id: 56,
+          pathname: "/blog",
+          timestamp: ~N[2020-01-02 00:01:00],
+          scroll_depth: 20
+        ),
+        build(:pageview, user_id: 56, pathname: "/another", timestamp: ~N[2020-01-02 00:01:00]),
+        build(:pageleave,
+          user_id: 56,
+          pathname: "/another",
+          timestamp: ~N[2020-01-02 00:02:00],
+          scroll_depth: 24
+        )
+      ])
+
+      conn =
+        post(conn, "/api/v2/query-internal-test", %{
+          "site_id" => site.domain,
+          "metrics" => ["scroll_depth"],
+          "date_range" => "all",
+          "dimensions" => ["event:page", "time:day"]
+        })
+
+      assert json_response(conn, 200)["results"] == [
+               %{"dimensions" => ["/blog", "2020-01-01"], "metrics" => [40]},
+               %{"dimensions" => ["/another", "2020-01-01"], "metrics" => [25]},
+               %{"dimensions" => ["/another", "2020-01-02"], "metrics" => [24]},
+               %{"dimensions" => ["/blog", "2020-01-02"], "metrics" => [20]}
+             ]
+    end
+  end
 end

test/plausible_web/controllers/api/stats_controller/main_graph_test.exs

@@ -584,6 +584,56 @@ defmodule PlausibleWeb.Api.StatsController.MainGraphTest do
     end
   end
 
+  describe "GET /api/stats/main-graph - scroll_depth plot" do
+    setup [:create_user, :log_in, :create_site]
+
+    test "returns 400 when scroll_depth is queried without a page filter", %{
+      conn: conn,
+      site: site
+    } do
+      conn =
+        get(
+          conn,
+          "/api/stats/#{site.domain}/main-graph?period=month&date=2021-01-01&metric=scroll_depth"
+        )
+
+      assert %{"error" => error} = json_response(conn, 400)
+      assert error =~ "can only be queried with a page filter"
+    end
+
+    test "returns scroll depth per day", %{conn: conn, site: site} do
+      t0 = ~N[2020-01-01 00:00:00]
+      [t1, t2, t3] = for i <- 1..3, do: NaiveDateTime.add(t0, i, :minute)
+
+      populate_stats(site, [
+        build(:pageview, user_id: 12, timestamp: t0),
+        build(:pageleave, user_id: 12, timestamp: t1, scroll_depth: 20),
+        build(:pageview, user_id: 34, timestamp: t0),
+        build(:pageleave, user_id: 34, timestamp: t1, scroll_depth: 17),
+        build(:pageview, user_id: 34, timestamp: t2),
+        build(:pageleave, user_id: 34, timestamp: t3, scroll_depth: 60),
+        build(:pageview, user_id: 56, timestamp: NaiveDateTime.add(t0, 1, :day)),
+        build(:pageleave,
+          user_id: 56,
+          timestamp: NaiveDateTime.add(t1, 1, :day),
+          scroll_depth: 20
+        )
+      ])
+
+      filters = Jason.encode!(%{page: "/"})
+
+      conn =
+        get(
+          conn,
+          "/api/stats/#{site.domain}/main-graph?period=7d&date=2020-01-07&metric=scroll_depth&filters=#{filters}"
+        )
+
+      assert %{"plot" => plot} = json_response(conn, 200)
+
+      assert plot == [40, 20, 0, 0, 0, 0, 0]
+    end
+  end
+
   describe "GET /api/stats/main-graph - conversion_rate plot" do
     setup [:create_user, :log_in, :create_site]
 

test/plausible_web/controllers/api/stats_controller/pages_test.exs

@@ -272,14 +272,16 @@ defmodule PlausibleWeb.Api.StatsController.PagesTest do
                  "visitors" => 2,
                  "pageviews" => 2,
                  "bounce_rate" => 0,
-                 "time_on_page" => 600
+                 "time_on_page" => 600,
+                 "scroll_depth" => 0
                },
                %{
                  "name" => "/blog/john-1",
                  "visitors" => 1,
                  "pageviews" => 1,
                  "bounce_rate" => 0,
-                 "time_on_page" => 60
+                 "time_on_page" => 60,
+                 "scroll_depth" => 0
                }
              ]
     end
@@ -334,14 +336,16 @@ defmodule PlausibleWeb.Api.StatsController.PagesTest do
                  "visitors" => 2,
                  "pageviews" => 2,
                  "bounce_rate" => 0,
-                 "time_on_page" => 120.0
+                 "time_on_page" => 120.0,
+                 "scroll_depth" => 0
                },
                %{
                  "name" => "/blog/other-post",
                  "visitors" => 1,
                  "pageviews" => 1,
                  "bounce_rate" => 0,
-                 "time_on_page" => nil
+                 "time_on_page" => nil,
+                 "scroll_depth" => 0
                }
              ]
     end
@@ -386,14 +390,16 @@ defmodule PlausibleWeb.Api.StatsController.PagesTest do
                  "visitors" => 2,
                  "pageviews" => 2,
                  "bounce_rate" => 50,
-                 "time_on_page" => 60
+                 "time_on_page" => 60,
+                 "scroll_depth" => 0
                },
                %{
                  "name" => "/blog/other-post",
                  "visitors" => 1,
                  "pageviews" => 1,
                  "bounce_rate" => 0,
-                 "time_on_page" => nil
+                 "time_on_page" => nil,
+                 "scroll_depth" => 0
                }
              ]
     end
@@ -442,14 +448,16 @@ defmodule PlausibleWeb.Api.StatsController.PagesTest do
                  "visitors" => 2,
                  "pageviews" => 2,
                  "bounce_rate" => 100,
-                 "time_on_page" => nil
+                 "time_on_page" => nil,
+                 "scroll_depth" => 0
                },
                %{
                  "name" => "/blog/john-1",
                  "visitors" => 1,
                  "pageviews" => 1,
                  "bounce_rate" => 0,
-                 "time_on_page" => 60
+                 "time_on_page" => 60,
+                 "scroll_depth" => 0
                }
              ]
     end
@@ -584,7 +592,49 @@ defmodule PlausibleWeb.Api.StatsController.PagesTest do
                  "visitors" => 2,
                  "pageviews" => 3,
                  "bounce_rate" => 50,
-                 "time_on_page" => 60
+                 "time_on_page" => 60,
+                 "scroll_depth" => 0
+               }
+             ]
+    end
+
+    test "calculates scroll_depth", %{conn: conn, site: site} do
+      t0 = ~N[2020-01-01 00:00:00]
+      [t1, t2, t3] = for i <- 1..3, do: NaiveDateTime.add(t0, i, :minute)
+
+      populate_stats(site, [
+        build(:pageview, user_id: 12, pathname: "/blog", timestamp: t0),
+        build(:pageleave, user_id: 12, pathname: "/blog", timestamp: t1, scroll_depth: 20),
+        build(:pageview, user_id: 12, pathname: "/another", timestamp: t1),
+        build(:pageleave, user_id: 12, pathname: "/another", timestamp: t2, scroll_depth: 24),
+        build(:pageview, user_id: 34, pathname: "/blog", timestamp: t0),
+        build(:pageleave, user_id: 34, pathname: "/blog", timestamp: t1, scroll_depth: 17),
+        build(:pageview, user_id: 34, pathname: "/another", timestamp: t1),
+        build(:pageleave, user_id: 34, pathname: "/another", timestamp: t2, scroll_depth: 26),
+        build(:pageview, user_id: 34, pathname: "/blog", timestamp: t2),
+        build(:pageleave, user_id: 34, pathname: "/blog", timestamp: t3, scroll_depth: 60),
+        build(:pageview, user_id: 56, pathname: "/blog", timestamp: t0),
+        build(:pageleave, user_id: 56, pathname: "/blog", timestamp: t1, scroll_depth: 100)
+      ])
+
+      conn = get(conn, "/api/stats/#{site.domain}/pages?period=day&date=2020-01-01&detailed=true")
+
+      assert json_response(conn, 200)["results"] == [
+               %{
+                 "name" => "/blog",
+                 "visitors" => 3,
+                 "pageviews" => 4,
+                 "bounce_rate" => 33,
+                 "time_on_page" => 60,
+                 "scroll_depth" => 60
+               },
+               %{
+                 "name" => "/another",
+                 "visitors" => 2,
+                 "pageviews" => 2,
+                 "bounce_rate" => 0,
+                 "time_on_page" => 60,
+                 "scroll_depth" => 25
                }
              ]
     end
@@ -631,14 +681,16 @@ defmodule PlausibleWeb.Api.StatsController.PagesTest do
                  "visitors" => 2,
                  "pageviews" => 3,
                  "bounce_rate" => 50,
-                 "time_on_page" => 60
+                 "time_on_page" => 60,
+                 "scroll_depth" => 0
                },
                %{
                  "name" => "/about",
                  "visitors" => 1,
                  "pageviews" => 1,
                  "bounce_rate" => 100,
-                 "time_on_page" => nil
+                 "time_on_page" => nil,
+                 "scroll_depth" => 0
                }
              ]
     end
@@ -685,7 +737,8 @@ defmodule PlausibleWeb.Api.StatsController.PagesTest do
                  "visitors" => 2,
                  "pageviews" => 3,
                  "bounce_rate" => 50,
-                 "time_on_page" => 60
+                 "time_on_page" => 60,
+                 "scroll_depth" => 0
                }
              ]
     end
@@ -731,21 +784,24 @@ defmodule PlausibleWeb.Api.StatsController.PagesTest do
                  "visitors" => 2,
                  "pageviews" => 2,
                  "bounce_rate" => 100,
-                 "time_on_page" => nil
+                 "time_on_page" => nil,
+                 "scroll_depth" => 0
                },
                %{
                  "name" => "/blog/post-1",
                  "visitors" => 1,
                  "pageviews" => 1,
                  "bounce_rate" => 0,
-                 "time_on_page" => 60
+                 "time_on_page" => 60,
+                 "scroll_depth" => 0
                },
                %{
                  "name" => "/blog/post-2",
                  "visitors" => 1,
                  "pageviews" => 1,
                  "bounce_rate" => 0,
-                 "time_on_page" => nil
+                 "time_on_page" => nil,
+                 "scroll_depth" => 0
                }
              ]
     end
@@ -783,14 +839,16 @@ defmodule PlausibleWeb.Api.StatsController.PagesTest do
                  "visitors" => 1,
                  "pageviews" => 1,
                  "bounce_rate" => 0,
-                 "time_on_page" => 60
+                 "time_on_page" => 60,
+                 "scroll_depth" => 0
                },
                %{
                  "name" => "/blog/(/post-2",
                  "visitors" => 1,
                  "pageviews" => 1,
                  "bounce_rate" => 0,
-                 "time_on_page" => nil
+                 "time_on_page" => nil,
+                 "scroll_depth" => 0
                }
              ]
     end
@@ -836,14 +894,16 @@ defmodule PlausibleWeb.Api.StatsController.PagesTest do
                  "visitors" => 2,
                  "pageviews" => 2,
                  "bounce_rate" => 50,
-                 "time_on_page" => 600
+                 "time_on_page" => 600,
+                 "scroll_depth" => 0
                },
                %{
                  "name" => "/about",
                  "visitors" => 1,
                  "pageviews" => 1,
                  "bounce_rate" => 0,
-                 "time_on_page" => nil
+                 "time_on_page" => nil,
+                 "scroll_depth" => 0
                }
              ]
     end
@@ -937,14 +997,16 @@ defmodule PlausibleWeb.Api.StatsController.PagesTest do
                  "time_on_page" => 900.0,
                  "visitors" => 2,
                  "pageviews" => 2,
-                 "name" => "/"
+                 "name" => "/",
+                 "scroll_depth" => 0
                },
                %{
                  "bounce_rate" => 0,
                  "time_on_page" => nil,
                  "visitors" => 1,
                  "pageviews" => 1,
-                 "name" => "/some-other-page"
+                 "name" => "/some-other-page",
+                 "scroll_depth" => 0
                }
              ]
     end
@@ -984,7 +1046,8 @@ defmodule PlausibleWeb.Api.StatsController.PagesTest do
                  "name" => "/about",
                  "pageviews" => 2,
                  "time_on_page" => nil,
-                 "visitors" => 2
+                 "visitors" => 2,
+                 "scroll_depth" => 0
                }
              ]
     end
@@ -1063,14 +1126,16 @@ defmodule PlausibleWeb.Api.StatsController.PagesTest do
                  "name" => "/about-blog",
                  "pageviews" => 3,
                  "time_on_page" => 1140.0,
-                 "visitors" => 2
+                 "visitors" => 2,
+                 "scroll_depth" => 0
                },
                %{
                  "bounce_rate" => 0,
                  "name" => "/exit-blog",
                  "pageviews" => 1,
                  "time_on_page" => nil,
-                 "visitors" => 1
+                 "visitors" => 1,
+                 "scroll_depth" => 0
                }
              ]
     end
@@ -1418,17 +1483,20 @@ defmodule PlausibleWeb.Api.StatsController.PagesTest do
                    "pageviews" => 0,
                    "time_on_page" => 0,
                    "visitors" => 0,
+                   "scroll_depth" => 0,
                    "change" => %{
                      "bounce_rate" => nil,
                      "pageviews" => 100,
                      "time_on_page" => nil,
-                     "visitors" => 100
+                     "visitors" => 100,
+                     "scroll_depth" => 0
                    }
                  },
                  "name" => "/page2",
                  "pageviews" => 2,
                  "time_on_page" => nil,
-                 "visitors" => 2
+                 "visitors" => 2,
+                 "scroll_depth" => 0
                },
                %{
                  "bounce_rate" => 100,
@@ -1436,16 +1504,19 @@ defmodule PlausibleWeb.Api.StatsController.PagesTest do
                  "pageviews" => 1,
                  "time_on_page" => nil,
                  "visitors" => 1,
+                 "scroll_depth" => 0,
                  "comparison" => %{
                    "bounce_rate" => 100,
                    "pageviews" => 1,
                    "time_on_page" => nil,
                    "visitors" => 1,
+                   "scroll_depth" => 0,
                    "change" => %{
                      "bounce_rate" => 0,
                      "pageviews" => 0,
                      "time_on_page" => nil,
-                     "visitors" => 0
+                     "visitors" => 0,
+                     "scroll_depth" => 0
                    }
                  }
                }

test/plausible_web/controllers/api/stats_controller/top_stats_test.exs

@@ -892,7 +892,7 @@ defmodule PlausibleWeb.Api.StatsController.TopStatsTest do
     } do
       filters = Jason.encode!(%{page: "/A"})
 
-      [visitors, visits, pageviews, bounce_rate, time_on_page] =
+      [visitors, visits, pageviews, bounce_rate, time_on_page, scroll_depth] =
         conn
         |> get("/api/stats/#{site.domain}/top-stats?filters=#{filters}")
         |> json_response(200)
@@ -903,6 +903,7 @@ defmodule PlausibleWeb.Api.StatsController.TopStatsTest do
       assert %{"graph_metric" => "pageviews"} = pageviews
       assert %{"graph_metric" => "bounce_rate"} = bounce_rate
       assert %{"graph_metric" => "time_on_page"} = time_on_page
+      assert %{"graph_metric" => "scroll_depth"} = scroll_depth
     end
 
     test "returns graph_metric key for top stats with a goal filter", %{
@@ -960,6 +961,31 @@ defmodule PlausibleWeb.Api.StatsController.TopStatsTest do
              ]
     end
 
+    test "returns scroll_depth with a page filter", %{conn: conn, site: site} do
+      populate_stats(site, [
+        build(:pageview, user_id: 123, timestamp: ~N[2021-01-01 00:00:00]),
+        build(:pageleave, user_id: 123, timestamp: ~N[2021-01-01 00:00:10], scroll_depth: 40),
+        build(:pageview, user_id: 123, timestamp: ~N[2021-01-01 00:00:10]),
+        build(:pageleave, user_id: 123, timestamp: ~N[2021-01-01 00:00:20], scroll_depth: 60),
+        build(:pageview, user_id: 456, timestamp: ~N[2021-01-01 00:00:00]),
+        build(:pageleave, user_id: 456, timestamp: ~N[2021-01-01 00:00:10], scroll_depth: 80)
+      ])
+
+      filters = Jason.encode!(%{page: "/"})
+
+      conn =
+        get(
+          conn,
+          "/api/stats/#{site.domain}/top-stats?period=day&date=2021-01-01&filters=#{filters}"
+        )
+
+      res = json_response(conn, 200)
+
+      assert %{"name" => "Scroll depth", "value" => 70, "graph_metric" => "scroll_depth"} in res[
+               "top_stats"
+             ]
+    end
+
     test "page glob filter", %{conn: conn, site: site} do
       populate_stats(site, [
         build(:pageview, pathname: "/index"),

test/support/factory.ex

@@ -140,6 +140,10 @@ defmodule Plausible.Factory do
     Map.put(event_factory(attrs), :name, "pageview")
   end
 
+  def pageleave_factory(attrs) do
+    Map.put(event_factory(attrs), :name, "pageleave")
+  end
+
   def event_factory(attrs) do
     if Map.get(attrs, :acquisition_channel) do
       raise "Acquisition channel cannot be written directly since it's a materialized column."

test/test_helper.exs

@@ -7,6 +7,7 @@ Mox.defmock(Plausible.HTTPClient.Mock, for: Plausible.HTTPClient.Interface)
 Application.ensure_all_started(:double)
 
 FunWithFlags.enable(:channels)
+FunWithFlags.enable(:scroll_depth)
 # Temporary flag to test `read_team_schemas` flag on all tests.
 if System.get_env("TEST_READ_TEAM_SCHEMAS") == "1" do
   IO.puts("READS TEAM SCHEMAS")