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Determining Measures of Success in Point of Sale Interface Design

by Martin Ho , 15.07.2010

This article is re-posted from User Centric’s blog.

When designing for Point of Sale (POS) terminals, improved speed and accuracy are common critical measures of success.  Decreasing the time of completing transactions is achieved through well organized content, clear labels, minimizing the total distance the finger needs to travel to complete a transaction, and reducing the number of screens users need to access to complete a transaction.  Increasing order accuracy is achieved through clear, visual confirmation of pressed buttons, differentiation of similar buttons, and a clear display of information to verify the order.

In a high-volume, fast-paced environment, a reduction in order time, even seconds per transaction, multiplied by thousands of transactions a day, can add up to a significant increase in revenue.  Increased order accuracy also directly impacts customer satisfaction.  But are speed and accuracy always critical measures of success when designing for POS terminals?

Let’s consider a high-end restaurant.  This is a setting where patrons specifically expect their dining experience to be slower-paced.  The speed of entering an order is much less critical, if critical at all, but order accuracy is likely the most critical factor.  Customers have much higher expectations that their meal will be perfect.  Imagine a scenario where a server mistakenly inputs an order for one kind of soufflé instead of another… that’s a very big problem.

Sometimes, other factors are crucial. I used to volunteer in a charity gift shop that sells handcrafted items from around the world.  When a customer would check out, the POS interface would provide us product information to share with customers, where the product was made, the materials used to make the product, and any cultural meanings associated with the product.  In this scenario, the goal was much more than simply ringing up the sale; rather, there was a large emphasis on having the POS interface facilitate the dissemination of product information.

Another example that comes to mind is a small, specialty cheese and wine shop that I frequent.   As products are not tagged with SKUs, it took the clerk an extremely long time to locate the specific cheese on the POS.  One might suggest to the shop owner that there was a need to invest in a more advanced POS system, but even though I waited a little longer than would be ideal, the wait time was not long enough to upset me (I will admit that my patience is greater in this environment compared to fast-food environments).  The shop wasn’t at risk of losing a significant amount of money through poor customer experience, as there is never a long line of people waiting to check out.   For this shop, the ROI for investing in a new POS simply wouldn’t be there.

Bottom line: When redesigning POS terminals, knowing the following is absolutely critical: who the user is, in what type of environment the POS will be used, and the critical measure(s) of success.  Faster is not always better.

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