A diary entry is the core data element in a diary study; it represents each response that participants provide to prompts. How you structure this entry template directly affects both the quality of data collected and the effort required from participants. There are three types of diary entries that can be used in a study: closed, open-ended, and multimedia.

Closed Diary Entries

Closed questions restrict participants to a set of predefined responses (e.g., multiple choice or rating-scale questions). Closed questions require minimum effort from participants, and they are usually easy to map onto a quantitative measure.

Use structured entries to:

1. Track changes across time or compare experiences between features, tasks, participants, or study conditions.
2. Track behaviors by logging the frequency or duration of specific actions.
3. Run quick checkins to capture a consistent, lightweight response from participants each day.

Example: Nutrition App

Assume that you’re a researcher studying a nutrition app and your goal is to understand how daily meal recommendations affect users’ eating habits over time. Your research question could be:

Research Question

Does personalized nutritional feedback encourage users to make healthier food choices across several weeks?

To investigate this question, you could design diary entries that ask participants to log structured responses such as the following.

These structured questions provide quantitative feedback that reveals trends in usage and perceived value. Over the study period, they can show whether your app’s personalized recommendations influence participants’ eating patterns.

However, structured questions are less effective for uncovering the why behind those patterns. They can’t capture unexpected behaviors, emotions, or experiences that fall outside the predefined answer options. To address this gap, you can pair structured questions with a short open-ended follow up like “What influenced your food choices today?”

Open-Ended Diary Entries

Open-ended questions that invite participants to describe experiences, thoughts, or feelings in their own words and in as much detail as they’d like to share. They’re the most flexible type of diary question, but they require more effort from participants.

Open-ended questions are used in diary studies to allow participants to:

• Describe events.
• Give feedback or share thoughts about the event they logged.

Event Description (Event Logging)

Open-ended questions can act as the main input of your diary entry when you want participants to describe the event of interest in detail.

Use this format when you need to:

1. Capture detailed, real-world context around an event or task.
2. Explore how participants interpret, experience, or make decisions during key moments.
3. Uncover unexpected themes or problems you couldn’t predict in advance.

These questions work especially well during discovery research, when you’re still defining the problem space and don’t yet know what patterns exist. They often surface unexpected insights or behaviors and help shape future research questions or product directions.

End-of-Entry Comment (Reflection or Feedback)

Open-ended questions can also appear at the end of the full entry. These prompts let participants share anything that didn’t fit into the other questions in the diary entry.

Use this approach when you want to:

• Give participants a final opportunity to share issues, suggestions, or highlights.
• Capture broader feedback that might cut across multiple tasks or experiences.
• Encourage participants to surface unanticipated topics in their own words.

Example: Smart Speaker

Imagine you’re testing a new voice-command feature for your smart speaker. One of your goals is to understand how people use it for different activities throughout the day.

Research Question

How do users perceive the usefulness of their smart speaker across different activity types, such as entertainment, productivity, and shopping?

What helps or hinders them when completing tasks with voice commands?

You might begin your diary entry with a multiple-select question to identify which activities occurred.

Then, for each option selected, you can add an open-ended question that asks the participant to describe what they did.

You could follow up with a rating-scale question about that activity.

This combination lets participants log what they did and rate its usefulness. At the end, you can include a reflection prompt such as the following:

While free-form questions provide rich qualitative detail, they also come with tradeoffs that affect participant effort and data consistency. Open-ended questions typically require more effort from participants, so entries can vary in detail. Some participants may write only a few sentences, while others may include pages of information. 

When entries are too short, you might miss important details; when they are too long, participants may accidentally share personal or sensitive information. These variations can result in the need for additional followup questions or even a followup interview.

Additionally, open-ended questions can be harder to analyze: you might need to use techniques such as thematic analysis or you may have to manually extract quantitative measures out of them. (For example, if you wanted to count how many people used the speaker for the various entertainment activities that they reported, you would need to extract that information from the open-ended response.)

Multimedia diary entries request that participants share photos, screenshots, audio, or video to capture visual or contextual details that words alone can’t convey. They provide concrete examples of user behavior and let researchers see what participants see.

Use multimedia inputs when you need to:

• Understand visual or auditory context of user behavior.
• Capture moments that are difficult for participants to describe accurately in text (e.g., gestures, expressions, or layout).
• Identify usability issues, errors, or workarounds that occur naturally during use (in real-time).
• Support or validate self-reported data with visual examples from participants’ actual experiences.

Example: Cafeteria-Dining Study

Imagine you are a researcher studying cafeteria dining habits among university students. You want to understand the drivers and barriers to healthy eating among students, specifically focusing on the moment of choice and consumption.

Research Questions

What influences students’ meal choices in the cafeteria (e.g., taste, price, convenience, health)?

What situational factors (e.g., time pressure, social company) affect their decisions?

Your diary entry may include the following questions:  

In this scenario, the multimedia question can make it easier for participants to respond. Taking a quick picture of their meal is often faster and more natural than typing out a detailed description. Photos also give researchers an accurate view of what participants ate, including portion size and context, which would be difficult to capture through text alone.

However, multimedia is not always the easier option. Recording or uploading files can interrupt participants’ routines, especially when their environment or device makes it inconvenient to take photos or record videos. From an analysis standpoint, multimedia entries can also be more time-consuming for researchers. Reviewing, categorizing, and storing images or videos securely require additional steps compared to text responses, and image data often needs to be coded manually to extract patterns or quantify behaviors.

Because the effort required for multimedia varies, its inclusion should be carefully considered. Balance participant effort, analysis effort, and the accuracy of the data when deciding whether to include one.

Formula for a Strong Diary Entry

Balance the Question Types

Most diary studies don’t rely on just one question type. In practice, diary studies usually combine closed, open-ended, and sometimes multimedia questions to balance consistency with depth.

However, one thing to keep in mind is that not all questions are equal in participant effort and analysis effort. Some questions take more time to answer than others, but the general rule of thumb is to prioritize participant effort first, and analysis effort second.

Participant Effort

Participant effort refers to how much time and energy participants need to complete a diary entry. Closed questions generally require the least effort because they are quick to answer and reduce cognitive load. Open-ended questions demand recall, reflection, and typing, which can lead to fatigue if overused.

Multimedia questions can vary in the amount of participant effort. For example, in the student-dining study, participants can take a quick photo of their meal instead of typing what they ate. This task requires little effort and works especially well when diary entries are submitted through text messages. In contrast, recording an interaction with a smart speaker and uploading it to a cloud repository may interfere with the participant’s task and require a sizable effort.

Analysis Effort

Analysis effort refers to how much time and complexity researchers face when interpreting responses. Closed-ended questions are the easiest to code and compare. Open-ended questions require researchers to systematically code responses and identify key themes, which takes longer and can introduce bias. 

Multimedia data increases this complexity even further. For example, multimedia files can be harder to manage and store securely. When participants share videos or voice notes, researchers may need to transcribe or summarize the content before analysis, which adds time and cost. These files are then analyzed much like qualitative text responses, requiring researchers to code the material and identify patterns or themes.

When balancing question types, prioritize reducing participant effort before minimizing analysis effort. High-quality data comes from participants who can respond thoughtfully and consistently. If diary entries are too demanding, people may skip questions or rush their answers, leading to incomplete or unreliable insights that weaken the study’s overall conclusions.

Aim for 5–10 Minutes per Entry

Diary entries should be kept short to keep participants engaged and prevent burnout. Remember that participants will complete these entries repeatedly throughout your study, so long forms increase the risk of dropoff. Pilot your diary study to ensure it takes about 5–10 minutes to complete an entry. If it takes longer than 15 minutes, participants are likely to skip questions or abandon reporting altogether.

Balance Tradeoffs

Think carefully about what each format contributes to your research questions and goals. Sometimes your research might require higher-effort tasks to capture the right level of detail — and that’s okay. The key is to decide what’s truly necessary for your study and what’s “good enough” to help you make informed decisions.

You can mix and match question types based on those needs. If you make open-ended or multimedia questions optional, participants can skip them when they’re not relevant, which helps prevent dropoff. But if every question requires long or detailed responses, the effort can quickly build up and reduce participation over time. Ultimately, striking a balance between your study needs and participant effort will yield the most valuable insights.