An ML based mostly strategy to proactive advertiser churn prevention | by Pinterest Engineering | Pinterest Engineering Weblog | Might, 2023
6 min read
Erika Solar ML Engineer | Advertiser Development Modeling Group; Ogheneovo Dibie Engineering Supervisor | Advertiser Development Modeling Group
On this weblog submit, we describe a Machine Studying (ML) powered proactive churn prevention resolution that was prototyped with our small & medium enterprise (SMB) advertisers. Outcomes from our preliminary experiment recommend that we will detect future churn with a excessive diploma of predictive energy and consequently empower our gross sales companions in mitigating churn. ML-powered proactive churn prevention can obtain higher outcomes than conventional reactive handbook effort.
Like many ads-based companies, at Pinterest, we’re intently centered on minimizing advertiser churn on our platform. Historically, advertiser churn is addressed reactively. Particularly, a gross sales particular person reaches out to an advertiser solely after they’ve churned. This strategy is difficult as a result of it’s extremely tough to “resurrect” a buyer as soon as they go away the platform. To handle the challenges with addressing churn reactively, we current a ML-powered proactive strategy to advertiser churn discount. Particularly, we developed a mannequin that may predict the chance of advertiser churn within the close to future and empowered our gross sales workforce with insights from this mannequin to forestall in danger accounts from churning.
On this weblog, we cowl the:
- Churn prediction mannequin’s design and implementation
- Experimentation within the managed North America SMB phase
Our workforce constructed a ML mannequin to foretell advertiser’s churn chance within the subsequent 14 days. We use the Shapely Additive Rationalization (SHAP) bundle to estimate the mannequin’s options’ contribution to the churn prediction. We offer the mannequin churn prediction together with prime contributing options to gross sales. Gross sales makes use of this info to prioritize their effort to mitigate churn for advertisers in danger. We are going to discuss every part in additional element within the following subsections.
Mannequin Structure
The preliminary model of our mannequin is predicated on a snapshot Gradient Boosting Choice Tree (GBDT) structure. We selected GBDT for the next causes:
- GBDT is a broadly used mannequin with good efficiency on small to medium sized tabular knowledge* (our knowledge matches on this description).
- SHAP works nicely with GBDT to estimate options’ contributions.
- Mannequin characteristic significance is straightforward to generate with GBDT.
- It could additionally function a very good baseline mannequin for future mannequin enhancements, e.g. a sequential mannequin.
*Snapshot means we use all the data out there as much as a given timestamp to foretell the churn chance within the subsequent 14 days with respect to that timestamp.
Goal Variable
After thorough evaluation and session on the enterprise wants, we determined to make use of the next goal variable definition (see Determine 1).
For our use case, we distinguish between an energetic and churned advertiser as follows:
- Lively advertiser: spent within the final 7 days
- Churned advertiser: no spend within the final 7 days
We solely predict the churn chance for energetic advertisers. Particularly, we predict if they are going to churn within the subsequent 14 days.
Options
There are over 200 options used within the mannequin. These options are aggregated throughout totally different statistical measures–e.g. min, avg, max and so forth — over a spread of time home windows such because the previous week / month previous to the inference dates. We additionally embrace week over week and month over month change options to replicate current tendencies. These options might be grouped within the following classes:
- Efficiency: impressions**, clicks, conversions, conversion values, spend, price per 1000 impressions, price per click on, clickthrough charge
- Purpose: objective attainment ratio, distance to objective
- Finances: price range and utilization
- Advertisements supervisor actions: creates, edits, archives, customized stories
- Property: gross sales channel, nation, business, tenure, dimension, spend historical past
- Marketing campaign configuration: focusing on, bid technique, goal kind, marketing campaign finish date
**View greater than 1 second.
Characteristic Contribution
We use the SHAP library to estimate the characteristic contribution to mannequin chance output. Sigmoid of the sum of the options’ SHAP contribution is the same as mannequin chance. From SHAP characteristic contribution, we will know what the important thing drivers are of excessive churn chance. We then spotlight them for the Gross sales workforce to forestall churn.
We use an offline educated mannequin to deduce energetic advertisers’ churn chance each day.
Churn Threat Class
To assist the Gross sales workforce higher perceive the which means of the mannequin output, we classify accounts into three classes based mostly on their churn chance: excessive, medium, and low churn danger. Excessive churn danger captures the accounts which might be largely prone to churn with excessive precision. Medium churn danger captures the accounts which have a decrease chance of churn. Low churn danger comprises the ‘wholesome’ accounts which might be unlikely to churn within the subsequent 14 days. We choose the thresholds to outline totally different churn danger classes in keeping with the Gross sales workforce’s request of desired precision and recall. Extra particulars might be present in Experiment Outcome.
Our first experiment was centered on SMB accounts in North America which might be managed by Gross sales Account Managers (AMs). We cut up the advertisers randomly into therapy and management teams inside the experiment inhabitants. For the management group, we don’t make any modifications to the present Gross sales workforce procedures. For the therapy group, we supported the Gross sales workforce to forestall churn with the next info:
- Churn Threat Class: Excessive / medium / low churn danger
- Churn Motive Class. We categorized the detailed churn causes into coarse churn classes to ease understanding. The Gross sales workforce carried out investigations utilizing churn classes as instructions.
Experiment Success Metrics
Our experiment was evaluated based mostly on the next standards:
- Mannequin predictive energy, i.e. how nicely our mannequin is ready to establish advertisers which might be prone to churn
- Efficacy of churn prediction in churn discount
Mannequin Predictive Energy
With a purpose to decide the mannequin’s predictive energy, we in contrast its on-line efficiency on the management group (i.e. AMs who didn’t have entry to the churn predictions) to what we had noticed offline throughout growth (i.e. our out-of-sample analysis). Particularly, we measured mannequin efficiency based mostly on:
- Mannequin high quality: We in contrast the AUC-ROC and AUC-PR noticed on-line to offline.
- Churn danger segmentation: In session with gross sales, we decided thresholds for top, medium, and low churn danger classes in order that:
- Recall in excessive and medium churn danger must be above 70%.
- Precision in excessive churn danger must be round 70%.
This allows gross sales to seize most accounts prone to churning whereas additionally prioritizing the right way to work by means of them, i.e. excessive churn danger first (highest precision).
With respect to mannequin high quality, our outcomes point out that the AUC-ROC noticed on-line is inside 1% of the offline AUC-ROC and the net AUC-PR is inside 3% of the offline AUC-PR. This means that the mannequin’s predictive energy in figuring out at-risk accounts is akin to what we noticed offline.
When it comes to churn danger segmentation, our mannequin’s precision, recall, and proportion of the inhabitants captured inside the excessive and medium danger churn classes have been persistently inside 2–3% of our offline analysis. This means that the segmentation of account danger based mostly on churn chance have been in step with our offline analysis and gross sales expectations.
Efficacy of Churn Prediction in Advertiser Churn Discount
We noticed a 24% (statistically vital) discount within the churn charge of excessive tier pods*** in our experiment therapy group in comparison with the management. This means that accounts whose churn dangers have been uncovered to AMs have been much less prone to churn than people who weren’t.
*** In excessive tier pods, AMs handle about 50–70 accounts on common.
On this weblog submit, we illustrated the event and implementation of an ML-based resolution for proactive churn prevention at Pinterest. We’re additionally actively investigating sequential mannequin architectures reminiscent of Lengthy short-term reminiscence (LSTM) and Transformers, which can higher seize the utilization behaviors of advertisers and reduce the necessity for handbook characteristic engineering reminiscent of week-over-week or month-over-month characteristic aggregation utilized in our present mannequin.
Advertiser Development Modeling Group
- Engineering: Erika Solar, Ogheneovo Dibie, Keshava Subramanya, Mao Ye
- Product: Shailini Pandya
- Product Analytics/Knowledge Science: Alex Simons
Gross sales Group
- Product: Wesley Kwiecien, Grace Yun
- Gross sales Managers: Abby (Fromm) Lubarsky
Salesforce Group
- Engineering: Gayathri Varadarangan (She Her), Murthy Tumuluri, Phani Chimata, Gabriela Mihaila, Richard Wu
Optimization Workbench Group
- Engineering: Phil Value, Jordan Boaz, Lucilla Chalmer
- Product: Dan Marantz
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