We had a pilot test of usability testing. We only planned to do tests on desktop pc because that's what we think is the main device with the our user group.

After the pilot we had a feedback conversation with our teacher. One of the suggestions he made was that we should add some tasks that are done with the mobile device.

I disagreed immediately but couldn't come up with any good explanation why this is a bad thing. My opinion was not taken seriously because teacher is 'the pro'. Now I would like to know if this really is a standard testing method to have multiple devices in the same testing?

For me it slunds like finding issues here and there and not focusing anything. So you most likely find more issues but wouldn't it be more important to find the 'famous 80 % of the problems' with one device? In my opinion the experience with the first device affects to the use of second device because the system being tested is only a part of a website.

In our case we cannot have more participants.

  • 1
    What is the typical usage for your app? Will the same individual use both types of devices depending on their circumstances or is there distinct categories of users, some using only desktop, some using only mobile? Your test scenario should mirror as closely as possible what happens in real life. Nov 1, 2019 at 15:41
  • I agree with celine. The basic problem is that the first usage affects the second usage: users 'learn' the software, so behaviour you see on the second device will be affected by what they learnt on the first device.
    – PhillipW
    Oct 25, 2020 at 9:12

1 Answer 1


You have to look at your analytics. Always start with that. If 95% of your users are using an iPhone 7 to use your product, that is where you should invest resources and test.

If you don't have analytics, user interviews are key. Ask your users on what device is it most likely for them to use your product and design a solution for that.

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