Horrible example. Somebody saying that 15" is larger than 13" is not even close to comparable to here. On the other hand, somebody saying 15" is better than 13". That is when you venture into subjective land.
I have a feeling you didn't really examine the study in question. The charts are quite clear and are based entirely on subjective facts. The study says the iPhone has too little color. It also says the Galaxy has too much color. Then, in this thread we heard from people who prefer one of the screens and from people who prefer the other screen.
So that study IS just like my laptop example. It provided subjective facts and then people expressed their opinions based off of those. Exactly the same thing.