Conferences

In sample surveys, non-response rates are generally reported as an indicator measuring data quality. Unit non-response and item non-response rates are reported for individual questions and study variables. In the diaries, an episode is defined as a time slot denoted by the same code. Missing episodes are difficult to observe because respondents record activities and its duration into diaries by themselves. Unobserved item non-response arises when a respondent forgets to record an activity in the diary, and this situation occurs when, for instance, a person travels home from work and stops for shopping. If the shopping stop is not recorded then the number of episodes is two episodes too low. The average episode numbers describes then some kind of filling intensity of diary keeping and missing episodes are unobserved item nonresponse. Diaries are used to collect data on the simultaneous activities or secondary activities of individuals, who may as well forget to record it in a diary. The total of secondary activities can also describe the filling intensity of diaries, and it forms the same kind of measure for item nonresponse. A large number of episodes and a high total time of secondary activities indicate valid diary data. Respondent’s time use has an unwanted impact on this measure and, for example, persons with long working hours have usually fewer activities to report.

A quality indicator based on the number of episodes was studied using the diary data of the Finnish Time Use Survey, which was conducted using the guidelines of the Harmonised European Time Use Survey (HETUS). Around 20-25 activity episodes, on average, are usually regarded as a reasonable value for the indicator of well filled diaries. Comparisons can be made between the fourteen countries which made their time use surveys following the guide lines of the HETUS, but comparisons with other surveys, in which different diaries, days, instructions for diary keeping or coding are used, are not valid. In the countries included in the Harmonised Time Use Survey Database, the number of episodes was the highest in Sweden (26 episodes) and the lowest in France (19 episodes). The average total for secondary activities was 170-190 minutes, and slight correlation (from 0.11 to 0.34) was found between these quality measures. The amount for reported secondary activates was the highest in France (351 minutes) while the lowest total for simultaneous activities was reported in Spain (82 minutes). The number of episodes depended on gender, age and education level.