Use data from a variety of sources to inform your design—analytics, A/B tests, social media sentiment, customer service logs, sales data, surveys, interviews, usability tests, contextual research, and other studies.
Include numbers and context. Whether you call them quantitative and qualitative, studies and nonstudies, or Big Data and thick data, you need the numbers and the context to tell the real story.
Ensure that data is sensitive to the complexity of the human experience. Use averages sparingly, infer with caution, corroborate liberally.
Use data to track changes over time, explore new patterns, and dig deeper on problems