Leanna Leung



Mobile iOS Usability Testing: Design for Decision-Making 


Designing for Decision-Making

To read the full version of my case study, check out my original post on Medium

Project Overview

Postmates is an on-demand delivery service best known for food delivery. The company has been steadily introducing and pushing more types of goods to users (e.g. clothing, gifts). 

The Goal

Conduct guerrilla usability tests on the Postmates iOS app to uncover pain points. I challenged myself to solve these pain points by helping users make decisions in a more effective way.

My Role

Sole designer :) As a personal project, I redesigned the iOS experience from research to prototype. I conducted usability tests, synthesized my findings, and designed & tested lo-fi and hi-fi prototypes. 



Mobile iOS

2 Weeks

My Process

I used Stanford/IDEO's design thinking framework to structure my problem solving:

1. Empathize


  • Most users use Postmates for food delivery 
  • Postmates seeks to further develop and promote deliveries of goods beyond food

Guerrilla Usability Testing

Assuming most users use Postmates for food delivery, I asked lunch-goers in the Financial District and Yerba Buena Metreon (food court) areas of San Francisco to ensure that users were in the right mindset (hungry). I asked users a few questions about their habits and behaviors, and had users complete three basic tasks using the Postmates app: 

  1. Choose a restaurant you would order from
  2. Add an item to your order
  3. Edit your order

2. Synthesis

Affinity Mapping

After testing with 7 users, I organized my findings with sticky notes and grouped my observations into themes to identify common pain points.

Prioritizing Needs

To identify the most salient problems, I evaluated each pain point along two dimensions: Importance to Users & Importance to Postmates. I based my evaluations on frequency, feasibility, and magnitude of impact.

This process revealed that the biggest points of friction occurred when users were deciding which merchant to order with. Once users made a decision, the rest of the ordering process was smooth sailing. So although task completion was high, frustration was equally high. 

Specifically, frustration stemmed from issues with two fundamental steps of effective decision-making: 1) identifying options, and 2) comparing the options. And at the root of these issues, respectively, are:

Problem B: A lack of information and functionality to efficiently analyze options - difficult to weigh options

  • Pain Point #3: Not enough merchant information upfront/available
  • Pain Point #4: Unable to sort, and thus compare options efficiently
  • Pain Point: #5: Merchant photos are not helpful or clear

Problem A: Confusing information architecture - difficult to identify options

  • Pain Point #1: Users didn’t know what Postmates Plus was
  • Pain Point #2: Unclear distinction between a curated list of merchants and an individual merchant


I annotated my findings below:

Developing Personas

Based on my research, I developed two personas that would help inform my designs. The key difference between the two types of users is their decision-making behavior. Some users have an idea of what they would like to order, while others have absolutely no clue.

Given my initial assumptions, these personas are based on my research with users who use the app for food delivery. That being said, I do consider Postmates’s goal to expand beyond food merchants in my designs, later on.

3. Ideate

After talking to users and understanding their needs, I was ready to think of solutions.


How might we help users make deliberate, thoughtful decisions in an efficient manner, while maximizing satisfaction?

Potential Solutions

Problem A: Confusing information architecture makes it difficult to identify options


Pain Point #1:
Users didn’t know what Postmates Plus was

Postmates Plus…does that mean I have to pay more?”


  • Rename 'Postmates Plus' to $3.99 Favorites', which is more reflective of what the feature is.
  • Clarify and make header text (feature description) more prominent.


  • Create 'Explore' tab/feature, one dedicated to lists of merchants and can serve as a centralized source of inspiration when users don't know what to order.
  • Remove 'Free' tab and turn into a pop-up on '$3.99 Favorites' (formerly 'Postmates Plus'), so that controls on the tab bar are consistent in function.

Pain Point #2:
Unclear distinction between a curated list of merchants and an individual merchant

These are my proposed changes to the information architecture:

Problem B: A lack of information and functionality to efficiently analyze options makes it difficult to weigh evidence


Provide price information and Yelp rating. Granted, pulling ratings from the Yelp API may not be completely feasible due to competition with Yelp's Yelp24 food delivery service. 

Pain Point #3:
Not enough merchant information upfront/available 


Add sort function to allow sorting by delivery time, price and (Yelp) rating. This will help both types of users (decisive, indecisive) streamline their selection process.

    Pain Point #4:
    Unable to sort, and thus compare options efficiently 



    • Replace merchant photos with aerial-view photos displaying multiple items.
    • Remove dark overlay.
    • Left-align and move info text below photos 

    Pain Point #5:
    Merchant photos are not helpful or clear  

    Task Flows

    To visualize the potential steps users could take and the impact of my proposed solutions, I created a task flow of the current app and another with my solutions implemented. 

    P2P Postmates Taskflow - Before FINAL FINAL.png

    4. Prototyping

    Lo-Fi UI Sketches

    With this improved task flow in mind, I began sketching wireframes of my solutions.





    Hi-Fi Prototype

    To test my hypothesis, I prototyped my potential solutions below. When applicable, I labeled my annotations with the corresponding pain point it addresses (listed again):

    • Pain Point #1: Unclear what Postmates Plus is
    • Pain Point #2: Unclear distinctions between a curated list or merchants and an individual merchants.
    • Pain Point #3: Not enough merchant information upfront/available, and difficult to read
    • Pain Point #4: No sort functionality. Unable to compare options in an efficient manner
    • Pain Point #5: Photos not robust enough to be helpful

    5. Validation


    • 2 out of 5 users were unsure of what the "$3.99 Favorites" and "Explore" tabs were at first. However, they understood once they tapped into the tab and read the header text.
    • 5 out of 5 users used the new sort function when prompted with scenarios, and found it helpful in expediting the selection process. (E.g. “Say you want to save money, what would you do?” User navigates to $3.99 Favorites tab and sorts by price.)


    To validate my redesigns, I asked 5 users to:

    • Complete tasks based on key decision-making factors (delivery fee, delivery time, price, rating) I found during research.
    • Tell me what they thought the controls on the bottom tab bar represented (Anywhere, $3.99 Favorites, Explore).


    Test my prototype out for yourself!



    To alleviate the slight confusion with the Explore tab, I changed the icon from a file cabinet to a star, and renamed it to be more reflective of the content it contains: "Featured" merchants.  

    Overall, with my changes, users were less frustrated and spent less time finding a merchant that met their needs! *fist bump*


    TLDR; Making decisions is tough. Decision-making within Postmates can be made easier by 1) simplifying the information architecture and 2) making information easily accessible to analyze.

    This exercise was a great opportunity for me to explore tackling issues of scale. As companies grow their offerings, they’ll want to help users make decisions amongst the options. Otherwise, users won’t make a choice at all.

    Since design is all about making deliberate choices, it was a fun challenge essentially decision-making for decision-making.