We collected the feedback from a customer satisfaction survey conducted after the product release. It was a good start, but there is room for improvement in determining the success of the POS system.

• Complicated POS system

• Inaccurate inventory data

• Receipt printing speed

• Slow payment process or system malfunction

• Counting money

• Taking/tracking orders quickly

• Easy inventory management

• Customer loyalty program

During the usability testing, I asked participants to describe what each icon, image, link, and button meant on the home screen. Surprisingly, none of the five participants noticed the discount icon immediately. They only discovered it after tapping on it. I had thought the discount outlined icon was clear and universal, but the test results suggested otherwise. In response, I made some slight changes to the icon's shape and ran another test, which produced better results.

At that time, I also needed to add more menus to the navigation bar. I suggested placing frequently used icons on the navigation bar and grouping the remaining menus inside a "more vertical" icon. To accomplish this, I used a slide-in bottom popup interaction.

Based on user feedback, people had trouble finding the order list or cart on the app. Users didn't notice the number of newly added items, even though the number of items was indicated in the top right icon. Consequently, they were only aware of the list screen once they tapped the icon. This issue was resolved by adding an animation that draws the user's attention after entering items in the cart. This solution was identified through consistent feedback from both internal and external user testing. After making this change, all users were able to find the order list and understand the number of items in the cart.

I designed the scanner interaction to focus on success and failure states after scanning an item and to improve scanning speed by eliminating checkout process time. However, during testing, we found that the scanner was too sensitive and sometimes scanned the same item multiple times, so we added a 'scan next item' button to prevent accidental scanning. After testing and iterating, we chose option C, with a 10/10 result, and proceeded with this interaction.

(Top) SUS total score (Left) Usertesting.com screen  (Right) The SUS score calculation 

To measure user experience (UX), I created design mockups and converted them into interactive prototypes. I then tested them using the System Usability Score (SUS), which involved asking ten questions rated on a scale of 1-5. Calculating the SUS scores transformed subjective feedback into quantifiable data, making it easier to measure people's responses. My checkout task scored 78.75 out of 100, indicating it was good enough to launch. Similarly, my refund task scored 82.20 out of 100, which was excellent to launch.