Usability Study on Fitbit

UW HCDE 517 Usability Studies


I conducted a diary study on a Fitbit wearable device for Samsung Research America. With a team of three, we investigated how experienced and novice users incorporated Fitbit into their lives over one week, and analyzed how they differed. Our primary goal was to understand why users continue to use Fitbit and why they stop. The objective was to inform Samsung on their development of new tools and services for managing weight.

The project involved synthesizing previous research studies, developing a rigorous study plan, executing the study with 10 participants, and analyzing and presenting our findings and recommendations to our client. Our study explored how wearable devices can help prevent chronic diseases such as diabetes through weight management.

Due to the NDA (non-disclosure agreement), I will only include our method and approach. Specific findings and recommendations are excluded.

Collaborators: Kim Lambert, Meena Sujanani, and Jessica Bao

My role: Primarily responsible for literature review, competitive analysis, participant screener, and synthesizing findings. I also took leadership in the day-to-day diary study implementation and facilitating project definition.

Project Links

  1. User Profile for Recruitment (PDF)
  2. Project Personas (PDF)
  3. Project Study Plan (PDF)
  4. Final Report (PDF)

*I’ve rewritten most sections of these documents for clarity prior to posting them here.

Kim Affinity Diagram

Kim grouping motivations of user subgroups during affinity diagramming.


Rather than conducting a standard usability test, our stakeholder at Samsung Research America expressed an interest in studying how people use apps for weight management, which ones resonate with them, and why. In particular, she was interested in comparing different approaches to weight management, and what factors influence long-term user retention in hopes of leveraging our findings to inform product strategy.

To meet the needs of the class and the stakeholder, we determined that a diary study on wearable device usage would help us understand the emerging behaviors within this burgeoning market.

Specifically, we investigated what motivates people to begin tracking their weight, the obstacles they faced while doing so, and which features encourage them to continue tracking.


We first performed a literature review and online competitive analysis of various wearable devices on the market to inform our study plan. We selected Fitbit Flex to use in our study based on its marketshare and feature set.

Then, we further segmented our audience based on their motivations for managing weight, and developed user profiles in order to identify our target audiences. Our profiles focused on two main user groups: novice users, who have neither used a Fitbit nor any other smart wearable devices; and experienced users, who have used their Fitbit device for at least 3 months. We created an online screener, and relied on convenience sampling for recruitment. We selected a total of 10 participants: 5 experienced users and 5 novice users.

User Persona

Persona for experienced user. Design by Jessica Bao.

We constructed our 7-day diary study in which participants received daily prompts through email. The prompts contained a set of same core questions, as well as a set of variable questions specific to each participant group. Each day of the study covered a different theme regarding device use. We avoided event- and signal-contingent protocol to allow more flexibility during the day for participants to record their experiences.

A sample of diary study questions we used.

A sample of diary study questions we used.

We followed up with post-study interviews in which we inquired in-depth about some diary study responses that were particularly interesting.

After data collection, we analyzed and synthesized our findings. We developed high-level recommendations that we presented to our stakeholder, along with her manager and the design team.


We produced 11 findings, each with an incidence rate and 1-2 representative quotes from novice and experienced participants. From those, we came up with 9 high-level recommendations that summarized our findings.

Lessons Learned

The challenging part about this project was its ambiguous nature. Our scope was broad and undefined, but through this process, I learned to clearly scope, plan, and execute a research study. I found this valuable because I gained skills to deliver a specific outcome to a real stakeholder. The biggest lesson I learned was to get buy-in for the research design prior to planning for execution. The expectation should line up; otherwise you might have to refine parts of the study and delay the timeline.

The project also taught me how to effectively communicate to stakeholders. I learned to communicate research findings at an appropriate level of detail, as well as ensure that the recommendations were relevant to their decision-making.

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