Pinnability: Machine learning in the home feed

Pinterest Engineering
8 min readadvanced
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Overview

The article discusses Pinnability, a machine learning initiative by Pinterest aimed at enhancing the personalization of the home feed by predicting which Pins users are likely to engage with. It details the methodologies employed, including various machine learning models, and highlights the significant improvements in user engagement metrics since its implementation.

What You'll Learn

1

How to implement machine learning models for personalized content recommendations

2

Why using relevance scores improves user engagement on platforms like Pinterest

3

How to generate training instances from user interaction data

4

When to apply online training to machine learning models for real-time adjustments

Prerequisites & Requirements

  • Understanding of machine learning concepts and models
  • Familiarity with data processing frameworks like MapReduce(optional)

Key Questions Answered

What is Pinnability and how does it enhance the home feed experience on Pinterest?
Pinnability is a set of machine learning models developed by Pinterest to predict the relevance of Pins for individual users. By scoring Pins based on their likelihood of engagement, it allows Pinterest to prioritize personalized content in the home feed, significantly improving user interaction and satisfaction.
What machine learning models are used in the Pinnability system?
The Pinnability system utilizes several advanced machine learning models including Logistic Regression, Support Vector Machines, Gradient Boosted Decision Trees, and Convolutional Neural Networks. These models analyze thousands of features to accurately predict user engagement with Pins.
How does Pinterest generate training data for the Pinnability models?
Pinterest generates training data by recording user interactions with Pins in the home feed, including likes, repins, and clicks. This data is then sampled to create a balanced dataset of positive and negative interactions, which is used to train the Pinnability models.
What improvements have been observed since the launch of Pinnability?
Since launching Pinnability, Pinterest has seen a more than 20 percent increase in the home feed repinner count, along with significant gains in total repins and clickthroughs. This indicates a substantial boost in user engagement due to the personalized content delivery.

Key Statistics & Figures

Increase in home feed repinner count
more than 20 percent
Observed since the launch of Pinnability
Average AUC score of Pinnability model
around 90 percent
Indicates the model's effectiveness in predicting user engagement

Technologies & Tools

Machine Learning
Logistic Regression
Used as one of the models to predict user engagement with Pins
Machine Learning
Support Vector Machines
Another model employed in the Pinnability system for prediction
Machine Learning
Gradient Boosted Decision Trees
Utilized for enhancing the accuracy of engagement predictions
Machine Learning
Convolutional Neural Networks
Applied for extracting visual features from Pins
Data Processing
Mapreduce
Used for generating training instances from large datasets

Key Actionable Insights

1
Implementing machine learning models for content recommendations can significantly enhance user engagement.
By utilizing models like Logistic Regression and Gradient Boosted Decision Trees, platforms can tailor content to user preferences, leading to increased interaction and satisfaction.
2
Generating training instances from user interactions is crucial for building effective recommendation systems.
Understanding how users interact with content allows for the creation of more accurate predictive models, which can adapt to changing user behaviors over time.
3
Regularly evaluating and updating machine learning models based on user engagement metrics is essential.
Monitoring the performance of models through A/B testing ensures that the recommendations remain relevant and effective, adapting to new data and user preferences.

Common Pitfalls

1
Failing to regularly update machine learning models can lead to outdated predictions that do not reflect current user preferences.
Without continuous evaluation and adjustment, models may become less effective over time, resulting in decreased user engagement.
2
Overfitting models to historical data can reduce their generalization to new user interactions.
It's important to balance model complexity and training data to ensure that predictions remain relevant across diverse user behaviors.