add conversion-metrics-docs (#4724)

## What are you changing in this pull request and why?  ## Checklist  - [ ] Review the [Content style guide](https://github.com/dbt-labs/docs.getdbt.com/blob/current/contributing/content-style-guide.md) so my content adheres to these guidelines. - [ ] For [docs versioning](https://github.com/dbt-labs/docs.getdbt.com/blob/current/contributing/single-sourcing-content.md#about-versioning), review how to [version a whole page](https://github.com/dbt-labs/docs.getdbt.com/blob/current/contributing/single-sourcing-content.md#adding-a-new-version) and [version a block of content](https://github.com/dbt-labs/docs.getdbt.com/blob/current/contributing/single-sourcing-content.md#versioning-blocks-of-content). - [ ] Add a checklist item for anything that needs to happen before this PR is merged, such as "needs technical review" or "change base branch." Adding or removing pages (delete if not applicable): - [ ] Add/remove page in `website/sidebars.js` - [ ] Provide a unique filename for new pages - [ ] Add an entry for deleted pages in `website/static/_redirects` - [ ] Run link testing locally with `npm run build` to update the links that point to deleted pages
dbt-labs · Jan 16, 2024 · 32d7b1d · 32d7b1d
2 parents 5f39650 + f26fc84
commit 32d7b1d
Show file tree

Hide file tree

Showing 6 changed files with 376 additions and 1 deletion.
diff --git a/website/docs/docs/build/about-metricflow.md b/website/docs/docs/build/about-metricflow.md
@@ -63,6 +63,7 @@ Metrics, which is a key concept, are functions that combine measures, constraint
 
 MetricFlow supports different metric types:
 
+- [Conversion](/docs/build/conversion) &mdash; Helps you track when a base event and a subsequent conversion event occurs for an entity within a set time period.
 - [Cumulative](/docs/build/cumulative) &mdash;  Aggregates a measure over a given window.
 - [Derived](/docs/build/derived) &mdash; An expression of other metrics, which allows you to do calculations on top of metrics.
 - [Ratio](/docs/build/ratio) &mdash; Create a ratio out of two measures, like revenue per customer.

diff --git a/website/docs/docs/build/conversion-metrics.md b/website/docs/docs/build/conversion-metrics.md
@@ -0,0 +1,351 @@
+---
+title: "Conversion metrics"
+id: conversion
+description: "Use Conversion metrics to measure conversion events."
+sidebar_label: Conversion
+tags: [Metrics, Semantic Layer]
+---
+
+Conversion metrics allow you to define when a base event and a subsequent conversion event happen for a specific entity within some time range.
+
+For example, using conversion metrics allows you to track how often a user (entity) completes a visit (base event) and then makes a purchase (conversion event) within 7 days (time window). You would need to add a time range and an entity to join. 
+
+Conversion metrics are different from [ratio metrics](/docs/build/ratio) because you need to include an entity in the pre-aggregated join.
+
+## Parameters
+
+The specification for conversion metrics is as follows:
+
+| Parameter | Description | Type | Required/Optional |
+| --- | --- | --- | --- |
+| `name` | The name of the metric. | String | Required |
+| `description` | The description of the metric. | String | Optional |
+| `type` | The type of metric (such as derived, ratio, and so on.). In this case, set as 'conversion' | String | Required |
+| `label` | Displayed value in downstream tools. | String | Required |
+| `type_params` | Specific configurations for each metric type. | List | Required |
+| `conversion_type_params` | Additional configuration specific to conversion metrics. | List  | Required |
+| `entity` | The entity for each conversion event. | Entity | Required |
+| `calculation` | Method of calculation. Either `conversion_rate` or `conversions`. Defaults to `conversion_rate`. | String | Optional |
+| `base_measure` | The base conversion event measure. | Measure | Required |
+| `conversion_measure` | The conversion event measure. | Measure | Required |
+| `window` | The time window for the conversion event, such as 7 days, 1 week, 3 months. Defaults to infinity.  | String | Optional |
+| `constant_properties` | List of constant properties.  | List | Optional |
+| `base_property` | The property from the base semantic model that you want to hold constant.  | Entity or Dimension | Optional |
+| `conversion_property` | The property from the conversion semantic model that you want to hold constant.  | Entity or Dimension | Optional |
+
+The following code example displays the complete specification for conversion metrics and details how they're applied:
+
+```yaml
+metrics:
+  - name: The metric name # Required
+    description: the metric description # Required
+    type: conversion
+    type_params:
+      conversion_type_params:
+        entity: ENTITY # Required
+        calculation: CALCULATION_TYPE # Optional. default: conversion_rate. options: conversions(buys) or conversion_rate (buys/visits), and more to come.
+        base_measure: MEASURE # Required
+        conversion_measure: MEASURE # Required
+        window: TIME_WINDOW # Optional. default: infinity. window to join the two events. Follows a similar format as time windows elsewhere (such as 7 days)
+        constant_properties: # Optional. List of constant properties default: None
+          - base_property: DIMENSION or ENTITY # Required. A reference to a dimension/entity of the semantic model linked to the base_measure
+            conversion_property: DIMENSION or ENTITY # Same as base above, but to the semantic model of the conversion_measure
+```
+
+## Conversion metric example
+
+The following example will measure conversions from website visits (`VISITS` table) to order completions (`BUYS` table) and calculate a conversion metric for this scenario step by step.
+
+Suppose you have two semantic models, `VISITS` and `BUYS`:
+
+- The `VISITS` table represents visits to an e-commerce site.
+- The `BUYS` table represents someone completing an order on that site.  
+
+The underlying tables look like the following:
+
+`VISITS`<br />
+Contains user visits with `USER_ID` and `REFERRER_ID`.
+
+| DS | USER_ID | REFERRER_ID |
+| --- | --- | --- |
+| 2020-01-01 | bob | facebook |
+| 2020-01-04 | bob | google |
+| 2020-01-07 | bob | amazon |
+
+`BUYS`<br />
+Records completed orders with `USER_ID` and `REFERRER_ID`.
+
+| DS | USER_ID | REFERRER_ID |
+| --- | --- | --- |
+| 2020-01-02 | bob | facebook |
+| 2020-01-07 | bob | amazon |
+
+Next, define a conversion metric as follows:
+
+```yaml
+- name: visit_to_buy_conversion_rate_7d
+  description: "Conversion rate from visiting to transaction in 7 days"
+  type: conversion
+  label: Visit to Buy Conversion Rate (7-day window)
+  type_params:
+    conversion_type_params:
+      base_measure: visits
+      conversion_measure: sellers
+      entity: user
+      window: 7 days
+```
+
+To calculate the conversion, link the `BUYS` event to the nearest `VISITS` event (or closest base event). The following steps explain this process in more detail:
+
+### Step 1: Join `VISITS` and `BUYS`
+
+This step joins the `BUYS` table to the `VISITS` table and gets all combinations of visits-buys events that match the join condition where buys occur within 7 days of the visit (any rows that have the same user and a buy happened at most 7 days after the visit).
+
+The SQL generated in these steps looks like the following:
+
+```sql
+select
+  v.ds,
+  v.user_id,
+  v.referrer_id,
+  b.ds,
+  b.uuid,
+  1 as buys
+from visits v
+inner join (
+    select *, uuid_string() as uuid from buys -- Adds a uuid column to uniquely identify the different rows
+) b
+on
+v.user_id = b.user_id and v.ds <= b.ds and v.ds > b.ds - interval '7 day'
+```
+
+The dataset returns the following (note that there are two potential conversion events for the first visit):
+
+| V.DS | V.USER_ID | V.REFERRER_ID | B.DS | UUID | BUYS |
+| --- | --- | --- | --- | --- | --- |
+| 2020-01-01 | bob | facebook | 2020-01-02 | uuid1 | 1 |
+| 2020-01-01 | bob | facebook | 2020-01-07 | uuid2 | 1 |
+| 2020-01-04 | bob | google | 2020-01-07 | uuid2 | 1 |
+| 2020-01-07 | bob | amazon | 2020-01-07 | uuid2 | 1 |
+
+### Step 2: Refine with window function
+
+Instead of returning the raw visit values, use window functions to link conversions to the closest base event. You can partition by the conversion source and get the `first_value` ordered by `visit ds`, descending to get the closest base event from the conversion event:
+
+```sql
+select
+  first_value(v.ds) over (partition by b.ds, b.user_id, b.uuid order by v.ds desc) as v_ds,
+  first_value(v.user_id) over (partition by b.ds, b.user_id, b.uuid order by v.ds desc) as user_id,
+  first_value(v.referrer_id) over (partition by b.ds, b.user_id, b.uuid order by v.ds desc) as referrer_id,
+  b.ds,
+  b.uuid,
+  1 as buys
+from visits v
+inner join (
+    select *, uuid_string() as uuid from buys
+) b
+on
+v.user_id = b.user_id and v.ds <= b.ds and v.ds > b.ds - interval '7 day'
+
+```
+
+The dataset returns the following:
+
+| V.DS | V.USER_ID | V.REFERRER_ID | B.DS | UUID | BUYS |
+| --- | --- | --- | --- | --- | --- |
+| 2020-01-01 | bob | facebook | 2020-01-02 | uuid1 | 1 |
+| 2020-01-07 | bob | amazon | 2020-01-07 | uuid2 | 1 |
+| 2020-01-07 | bob | amazon | 2020-01-07 | uuid2 | 1 |
+| 2020-01-07 | bob | amazon | 2020-01-07 | uuid2 | 1 |
+
+This workflow links the two conversions to the correct visit events. Due to the join, you end up with multiple combinations, leading to fanout results. After applying the window function, duplicates appear. 
+
+To resolve this and eliminate duplicates, use a distinct select. The UUID also helps identify which conversion is unique. The next steps provide more detail on how to do this.
+
+### Step 3: Remove duplicates
+
+Instead of regular select used in the [Step 2](#step-2-refine-with-window-function), use a distinct select to remove the duplicates:
+
+```sql
+select distinct
+  first_value(v.ds) over (partition by b.ds, b.user_id, b.uuid order by v.ds desc) as v_ds,
+  first_value(v.user_id) over (partition by b.ds, b.user_id, b.uuid order by v.ds desc) as user_id,
+  first_value(v.referrer_id) over (partition by b.ds, b.user_id, b.uuid order by v.ds desc) as referrer_id,
+  b.ds,
+  b.uuid,
+  1 as buys
+from visits v
+inner join (
+    select *, uuid_string() as uuid from buys
+) b
+on
+v.user_id = b.user_id and v.ds <= b.ds and v.ds > b.ds - interval '7 day';
+```
+
+The dataset returns the following:
+
+| V.DS | V.USER_ID | V.REFERRER_ID | B.DS | UUID | BUYS |
+| --- | --- | --- | --- | --- | --- |
+| 2020-01-01 | bob | facebook | 2020-01-02 | uuid1 | 1 |
+| 2020-01-07 | bob | amazon | 2020-01-07 | uuid2 | 1 |
+
+You now have a dataset where every conversion is connected to a visit event. To proceed:
+
+1. Sum up the total conversions in the "conversions" table.
+2. Combine this table with the "opportunities" table, matching them based on group keys.
+3. Calculate the conversion rate.
+
+### Step 4: Aggregate and calculate
+
+Now that you’ve tied each conversion event to a visit, you can calculate the aggregated conversions and opportunities measures. Then, you can join them to calculate the actual conversion rate. The SQL to calculate the conversion rate is as follows:
+
+```sql
+select
+  coalesce(subq_3.metric_time__day, subq_13.metric_time__day) as metric_time__day,
+  cast(max(subq_13.buys) as double) / cast(nullif(max(subq_3.visits), 0) as double) as visit_to_buy_conversion_rate_7d
+from ( -- base measure
+  select
+    metric_time__day,
+    sum(visits) as mqls
+  from (
+    select
+      date_trunc('day', first_contact_date) as metric_time__day,
+      1 as visits
+    from visits
+  ) subq_2
+  group by
+    metric_time__day
+) subq_3
+full outer join ( -- conversion measure
+  select
+    metric_time__day,
+    sum(buys) as sellers
+  from (
+    -- ...
+    -- The output of this subquery is the table produced in Step 3. The SQL is hidden for legibility.
+    -- To see the full SQL output, add --explain to your conversion metric query. 
+  ) subq_10
+  group by
+    metric_time__day
+) subq_13
+on
+  subq_3.metric_time__day = subq_13.metric_time__day
+group by
+  metric_time__day
+```
+
+### Additional settings
+
+Use the following additional settings to customize your conversion metrics:
+
+- **Null conversion values:** Set null conversions to zero using `fill_nulls_with`.
+- **Calculation type:** Choose between showing raw conversions or conversion rate.
+- **Constant property:** Add conditions for specific scenarios to join conversions on constant properties.
+
+<Tabs>
+<TabItem value="null" label="Set null conversion events to zero">
+
+To return zero in the final data set, you can set the value of a null conversion event to zero instead of null. You can add the `fill_nulls_with` parameter to your conversion metric definition like this:
+
+```yaml
+- name: vist_to_buy_conversion_rate_7_day_window
+  description: "Conversion rate from viewing a page to making a purchase"
+  type: conversion
+  label: Visit to Seller Conversion Rate (7 day window)
+  type_params:
+    conversion_type_params:
+      calculation: conversions
+      base_measure: visits
+      conversion_measure: 
+        name: buys
+        fill_nulls_with: 0
+      entity: user
+      window: 7 days 
+
+```
+
+This will return the following results:
+
+<Lightbox src="/img/docs/dbt-cloud/semantic-layer/conversion-metrics-fill-null.png" width="75%" title="Conversion metric with fill nulls with parameter"/>
+
+</TabItem>
+
+<TabItem value="calctype" label="Set calculation type parameter">
+
+Use the conversion calculation parameter to either show the raw number of conversions or the conversion rate. The default value is the conversion rate.
+
+You can change the default to display the number of conversions by setting the `calculation: conversion` parameter:
+
+```yaml
+- name: visit_to_buy_conversions_1_week_window
+    description: "Visit to Buy Conversions"
+    type: conversion
+    label: Visit to Buy Conversions (1 week window)
+    type_params:
+      conversion_type_params:
+        calculation: conversions
+        base_measure: visits
+        conversion_measure: 
+          name: buys
+          fill_nulls_with: 0
+        entity: user
+        window: 1 week
+```
+
+</TabItem>
+
+<TabItem value="constproperty" label="Set constant property">
+
+*Refer to [Amplitude's blog posts on constant properties](https://amplitude.com/blog/holding-constant) to learn about this concept.*
+
+You can add a constant property to a conversion metric to count only those conversions where a specific dimension or entity matches in both the base and conversion events. 
+
+For example, if you're at an e-commerce company and want to answer the following question:
+- _How often did visitors convert from `View Item Details` to `Complete Purchase` with the same product in each step?_<br />
+  - This question is tricky to answer because users could have completed these two conversion milestones across many products. For example, they may have viewed a pair of shoes, then a T-shirt, and eventually checked out with a bow tie. This would still count as a conversion, even though the conversion event only happened for the bow tie.
+
+Back to the initial questions, you want to see how many customers viewed an item detail page and then completed a purchase for the _same_ product.
+
+In this case, you want to set `product_id` as the constant property. You can specify this in the configs as follows:
+
+```yaml
+- name: view_item_detail_to_purchase_with_same_item
+  description: "Conversion rate for users who viewed the item detail page and purchased the item"
+  type: Conversion
+  label: View Item Detail > Purchase
+  type_params:
+    conversion_type_params:
+      calculation: conversions
+      base_measure: view_item_detail
+      conversion_measure: purchase
+      entity: user
+      window: 1 week
+      constant_properties:
+        - base_property: product
+          conversion_property: product
+```
+
+You will add an additional condition to the join to make sure the constant property is the same across conversions.
+
+```sql
+select distinct
+  first_value(v.ds) over (partition by buy_source.ds, buy_source.user_id, buy_source.session_id order by v.ds desc rows between unbounded preceding and unbounded following) as ds,
+  first_value(v.user_id) over (partition by buy_source.ds, buy_source.user_id, buy_source.session_id order by v.ds desc rows between unbounded preceding and unbounded following) as user_id,
+  first_value(v.referrer_id) over (partition by buy_source.ds, buy_source.user_id, buy_source.session_id order by v.ds desc rows between unbounded preceding and unbounded following) as referrer_id,
+  buy_source.uuid,
+  1 as buys
+from {{ source_schema }}.fct_view_item_details v
+inner join
+  (
+    select *, {{ generate_random_uuid() }} as uuid from {{ source_schema }}.fct_purchases
+  ) buy_source
+on
+  v.user_id = buy_source.user_id
+  and v.ds <= buy_source.ds
+  and v.ds > buy_source.ds - interval '7 day'
+  and buy_source.product_id = v.product_id --Joining on the constant property product_id
+
+```
+
+</TabItem>
+</Tabs>
diff --git a/website/docs/docs/build/metrics-overview.md b/website/docs/docs/build/metrics-overview.md
@@ -48,6 +48,27 @@ This page explains the different supported metric types you can add to your dbt
 - [Ratio](#ratio-metrics) — Create a ratio out of two measures. 
 -->
 
+### Conversion metrics <Lifecycle status='new'/>
+
+[Conversion metrics](/docs/build/conversion) help you track when a base event and a subsequent conversion event occurs for an entity within a set time period.
+
+```yaml
+metrics:
+  - name: The metric name # Required
+    description: the metric description # Required
+    type: conversion
+    type_params:
+      conversion_type_params:
+        entity: ENTITY # Required
+        calculation: CALCULATION_TYPE # Optional. default: conversion_rate. options: conversions(buys) or conversion_rate (buys/visits), and more to come.
+        base_measure: MEASURE # Required
+        conversion_measure: MEASURE # Required
+        window: TIME_WINDOW # Optional. default: infinity. window to join the two events. Follows a similar format as time windows elsewhere (such as 7 days)
+        constant_properties: # Optional. List of constant properties default: None
+          - base_property: DIMENSION or ENTITY # Required. A reference to a dimension/entity of the semantic model linked to the base_measure
+            conversion_property: DIMENSION or ENTITY # Same as base above, but to the semantic model of the conversion_measure
+```
+
 ### Cumulative metrics 
 
 [Cumulative metrics](/docs/build/cumulative) aggregate a measure over a given window. If no window is specified, the window would accumulate the measure over all time. **Note**, you will need to create the [time spine model](/docs/build/metricflow-time-spine) before you add cumulative metrics.
@@ -66,6 +87,7 @@ metrics:
       window: 7 days
 
 ```
+
 ### Derived metrics
 
 [Derived metrics](/docs/build/derived) are defined as an expression of other metrics. Derived metrics allow you to do calculations on top of metrics.