Statistical significance vs Practical significance
when N is large, even a trivial difference (small effect) may be large enough to produce a statistically significant result
eg menu choice: mean selection time of menu a is 3 seconds; menu b is 3.05 seconds
Statistical significance does not imply that the difference is important!
a matter of interpretation, i.e., subjective opinion
should always report means to help others make their opinion
There are measures for effect size, regrettably they are not widely used in HCI research