A diary study is a UX research method where participants record their experiences and activities over a period of time in a journal or diary. The goal of a diary study is to capture the rich and nuanced experiences of users over time, in their natural environments.

Participants are typically given specific prompts or tasks to complete during the study period, which they record in their diaries. These prompts can include questions about their experiences using a particular product, interactions with other people or technology, or any other relevant activities.

Planning a Diary Study

• Define goals for the study. What long-term behavior are you studying and for how long. What data do you want to collect?
• Define the user group you want participants to come from.
• Decide on the frequency. How often do you want participants to log their responses? Every day, week, or based on specific events.
• Plan on the logistics of the diary study. -- How are participants going to give you their logs? Over email, a notebook, a mobile application? -- How are you going to give participants their tasks?

Benefits of a Diary Study

• Unmoderated: Can involve a larger participant group than moderated methods like interviews.
• Longitudinal: Diary studies happen over a longer period of time than other research methods like interviews, user interviews, and surveys. Because of this they can show changing perspectives and behaviors.
• Contextual: Because diary studies happen over time and are self-reported, they are often contextual for the user when they are interacting with the system. Diary studies allow researchers to capture user behavior and experiences as they occur naturally in the user's environment.
• Provides detailed insights: Participants can provide detailed descriptions of their experiences that might be missed in other research methods.
• Can uncover unexpected insights: Because participants are free to write about anything relevant to the study.
• Cost Effective: Although observational field studies will produce richer insights, diary studies can usually be cheaper while including more participants.
• Subjective Data: Since participants are self-reporting over time, diary studies produce rich, subjective data that is unlikely from other methods. It can also be higher quality subjective data than snapshot methods like surveys.