Does the recording of parallel activities in Time Use Diaries affect the way people report their main activities?

It is widely recognised that studies based ontime diaries form the most valid and reliabledata source concerning peoples' timeallocation, but it is also documented thatvarious designs give somewhat divergentresults. Usually both main activities andpossible parallel activities are captured intime diaries. Much research has been undertakento evaluate various aspects of the design ofsuch surveys, but there has been littlesystematic investigation on the possibleeffects of recording parallel activities on theway people report their main activities. Asmost analyses focus mainly on primaryactivities, validity in this area is of utmostimportance. Utilising the Norwegian Time UseStudy from 1990–1991 we discuss in this paper if,and possibly how, the registration of secondaryactivities influences the picture we get ofpeople's main activities. Also the role of theexamples presented to participants isinspected. Our findings indicate that therecording of parallel activities does affectthe way people report their main activities.Especially indistinct and fuzzy activities likechildcare, socialising and television viewingseem to be sensitive, but effects differ forwomen and men. Undoubtedly, information onsecondary activities is needed in order tofully reflect people's time patterns, but it isimportant that guidelines for diary keeping andexamples presented to participants aredeveloped carefully so that information onprimary activities is not distorted.