Self Checkout Usability Study
Assessing the usability of Costco’s self checkout stations
My Role
UX Researcher
UX Design Methods
• Field study
• User flowcharts
• Usability testing
Deliverables
• Research Findings and Recommendations slide deck
Problem
Costco piloted new self checkout stations in two warehouses. Despite being designed for self service, many users had difficulty checking out on their own and required assistance from a warehouse attendant to complete their purchase.
Objectives
(1) Identify customer pain points in self checkout process.
(2) Provide recommendations to solve problems and reduce attendant intervention.
Research
Research Questions
(1) What are users’ pain points with the current self checkout system?
(2) Why are users asking for help from warehouse attendants?
(3) What is unique about the Costco checkout experience?
Field Study
I visited one of the pilot locations in Gig Harbor, WA to observe Costco members interacting with the self checkout stations. I recorded observations for 37 users.
User scans card to begin process
Items are scanned and placed on belt
Payment is collected after all items are scanned
Field Study Findings
49% of users exhibited hesitation or confusion during the Payment step. On the payment screen, the user must select a generic Payment button on the station’s screen to continue to the next step. Commonly observed problems were:
• Users hovered their fingers over the Payment screen, looked around and eventually selected the Payment button to continue.
• Users swiped their credit card before selecting the Payment button and did not immediately understand that they needed to select the Payment button to activate the PIN pad.
• Users did not know what do during the Payment step and asked for assistance.
We concluded that this screen did not clearly convey the expected action to users.
User Flowcharts
After observing the self checkout process in the warehouse, I created a user flowchart of the steps. I considered ways to improve the payment step to make it more clear and whether we could eliminate any steps to speed up the process. After coming up with a few options, I created a proposed flow with the following changes:
• Combine the Welcome and Scan Membership Card steps so the user does not have to wait for motion sensor to detect them to start the process.
• During the Select Payment Method step, display different payment method options. This aligns with the audio prompt and the self-checkout pattern used by other retailers.
• Allow the user to swipe their credit card and continue with purchase without selecting a payment method during the Select Payment Method step. This aligns with the self-checkout pattern used by other retailers.
• Hide the Scan Coupons step unless activated by the user since coupons are rarely used at a Costco.
I reviewed the new process with the stakeholders for approval and the self checkout station vendor for technical feasibility. Both gave the green light to proceed with testing the new flow.
Design
Sketches
Using the new flow as a guideline, I began sketching concepts with another designer for the new screens. We retained most of the current design elements and ideated on how to display the payment options. Once we were satisfied with our sketches, we worked with a visual designer to help turn the sketches into hi-fidelity mockups.
Usability Testing
We created a mock self checkout station in our office. We used an iPad with an interactive prototype of the new screens as the checkout station and made a paper prototype of the PIN pad. One designer moderated the test while another gave the audio cues used by the real self checkout stations.
For the test, we asked participants to buy a couple items using our mock self checkout station.
Usability Test Findings
All users understood the new payment screen and successfully checked out without asking for assistance.
End Result
The usability test results gave the project team added confidence in the recommended UX changes. We continued to work with the stakeholders and vendor to refine the design and the following changes were implemented at the stations:
• Redesigned Welcome/Lane Open screen (provided by UX)
• Select Payment Method screen shown with accepted forms of payment (provided by UX)
• Coupons screen removed (UX suggestion)
The changes improved the experience and reduced attendant intervention during the payment step. A second field study was run after the changes were rolled out and only 5% of users were observed experiencing friction with the payment step, with just 4% of users asking for assistance to proceed.
Old payment screen
Redesigned payment screen