> 40 is not an adequate sample size. Not even close. Last time I looked for a study of a similar subject (I think I was looking for speed comparison between T9

> 40 is not an adequate sample size. Not even close. Last time I looked for a study of a similar subject (I think I was looking for speed comparison between T9 and multi-tap input), it was something like that too: 30 or 50 students given a short exercise. And then subdivided in several categories (T9 / multitap x novice / average /expert), which brought the size of each group way below 10. The measuring criteria were also a bit weird, concentrating on the number of errors and not on the time to get a correct result. They were surprised that they were getting sensibly different results from a former study they were quoting, which was also using ridiculously low sample size... I didn't find a proper study on that subject. I thought it would be easy to find, as it didn't seem to be a niche subject at all: on something that was in use by 100 of millions people... I was a bit appalled that such crappy papers were published, but even more by the fact that no good one was. No-one decided to run a proper one after seeing the poor ones. And don't get me started on 'meta' studies (there was one) which push the limits of laziness even further since they do no study at all and even don't reproduce or improve a former one; packing a variety of crappy studies doesn't make a good one, no more than running bloody abstract statistics over figures which were not harvested using similar methodology in the first place.