In one of the first usability tests I ever did, I met a lovely old lady who could not use a mouse. She kept lifting it in the air and pointing at the screen, speaking words of encouragement to the cursor. At the end of the test I got absolutely nothing, but she did think I was a “lovely boy” who should meet her granddaughter. Very quickly I learned the value of setting very clear criteria for participant recruitment.
That’s classic. Thankfully Damian Rees offers some tips to improve your results.