Data-driven models help mobile app designers understand best practices and trends, and can be used to make predictions about design performance and support the creation of adaptive UIs. This paper presents Rico, the largest repository of mobile app designs to date, created to support five classes of data-driven applications: design search, UI layout generation, UI code generation, user interaction modeling, and user perception prediction. To create Rico, we built a system that combines crowdsourcing and automation to scalably mine design and interaction data from Android apps at runtime. The Rico dataset contains design data from more than 9.7k Android apps spanning 27 categories. It exposes visual, textual, structural, and interactive design properties of more than 72k unique UI screens. To demonstrate the kinds of applications that Rico enables, we present results from training an autoencoder for UI layout similarity, which supports query- by-example search over UIs.

To evaluate the performance of mobile app designs, designers and researchers employ techniques such as A/B, usability, and analytics-driven testing. While these are all useful strategies for evaluating known designs, comparing many divergent solutions to identify the most performant remains a costly and difficult problem. This paper introduces a design performance testing approach that leverages existing app implementations and crowd workers to enable comparative testing at scale. This approach is manifest in ZIPT, a zero-integration performance testing platform that allows designers to collect detailed design and interaction data over any Android app -- including apps they do not own and did not build. Designers can deploy scripted tests via ZIPT to collect aggregate user performance metrics (e.g., completion rate, time on task) and qualitative feedback over third-party apps. Through case studies, we demonstrate that designers can use ZIPT's aggregate data and visualizations to understand the relative performance of interaction patterns found in the wild, and identify usability issues in existing Android apps.