This paper concerns analysis of time use data collected with daily diaries. The most frequently used indicators in international time use studies are three: the unspecific mean time spent on each activity, the specific mean time spent on each activity and the participation frequency (rate) of each activity. Currently, the second is interpreted as a measure of time spent on each activity by participants only, and the third as a rate between the number of the participants of an activity and the total sample. So, they are statistical indicators relating to a sample or a population of individuals. This article asserts that if this is true, then the obtained estimates are incorrect. They are correct if they concern events instead of individuals, but in this case the meaning of indicators is quite different.