The Day after: The Effect of Diary Timing on Time Data Analysis

As proved in psychological research, human memory is deceiving and we tend to forget certain events (see e.g. Kahneman, 2004), especially if they were of little importance – such as daily chores or random housework-related tasks. However, these minor episodes are important in time data analysis, as they can tell much about the differences in time-use patterns or time allocation across the society. This fact has important implications for the time-data validity. If filling in of the time-use diary is postponed by the respondent until, for instance, the day after the activities took place, the record is already subject to substantial distortions. Some episodes are simply being forgotten. It results in diminished sequence variability, and extended episodes of the ‘typical’ activities - at the expense of the less usual ones. What is more, it has an effect on the differences in time allocation as shown in cross-sectional analysis. The day when the diary was filled in can thus have a significant impact on the results as well as conclusions drawn from time-use research. Using the German Time Use Data 2001/2002 and Polish Time Use Data 2003/2004 (both surveys conducted within the Harmonized European Time Use Survey framework) we show how gender differences in time allocation differ depending on when the diary was filled in by the respondent. By the means of multivariate analysis we also show how sequence specificity (such as number of episodes and their duration) differs depending on whether the diary was filled in on the same day as the recorded one – or the day after.