I don't know how science can help you here. In the case of the improved fan design, well that's easily testable.
However, I don't want to go down the rabbit hole and argue social vs natural sciences.
I find it dumbfounding that in this day and age, people can still create rather arbitrary social experiments with only 49 people and then think they can draw grandiose conclusions from their "data".
Unfortunately, user studies are difficult to conduct in computer science mainly because it is difficult to get users that you can study. Like it or not, 49 people is actually a pretty big study relative to what is out there. For better or for worse, I have seen much smaller studies accepted/published by top tier conferences.
However, I don't want to go down the rabbit hole and argue social vs natural sciences.
I find it dumbfounding that in this day and age, people can still create rather arbitrary social experiments with only 49 people and then think they can draw grandiose conclusions from their "data".