StrategizequalitativeIntermediate

Longitudinal study: Diaries

Understand usage, habits, and evolution of product experience over time.

What it is

Main objective

Understand usage, habits, and evolution of product experience over time.

Detailed description

Diary Studies is a longitudinal methodology in which participants record their experiences, thoughts, and activities over an extended period, typically days to weeks. This technique allows capturing behaviors and attitudes in real context, revealing temporal usage patterns and external factors that influence user experience. Research demonstrates its value for understanding experience evolution over time (Nielsen Norman Group). It is especially useful for products with long usage cycles or behaviors that vary by context.

When it fits

When long-term usage needs to be investigated in real context.

•Regular-use products
•Longitudinal research
•Behavior changes
•Product adoption

Effort level

High

Recommended number of users

5–10 participants

What you gain and what you give up

Advantages

Natural context and longitudinality: It is the best technique for understanding behaviors that occur over days or weeks in the user's real environment, minimizing the artificiality of the lab.
Captures the invisible: It provides access to the user's internal thoughts, doubts, and motivations at the exact moment they occur.
Evaluates expert use: It is ideal for seeing how users move from novice to intermediate or expert, something standard usability tests cannot measure.
Inspiration: It provides rich, human material (photos, anecdotes) that inspires the design team.

Disadvantages

Self-report bias: Participants may forget to log things, filter information to appear more competent, or rationalize their actions. It depends on the user's honesty and memory.
Participant fatigue: It requires a high level of commitment from the user. Data quality can decline over time if the participant gets tired.
Laborious analysis: It generates a large amount of unstructured data. The analysis can be "heavyweight," requiring a lot of time to code and synthesize information from multiple participants.
Lack of direct observation: The researcher does not see what actually happens, only what the user decides to report.