A City Guide To Gaogou for For example, rather than defining exercise in terms of organised activity, it could be defined as any physical activity that requires energy expenditure; or in terms of drinking alcohol, whether a drink’ is defined and counted in terms of standard units’ see alcohol section, or size of glass, or strength of alcohol. The definition adopted will influence the questions asked, and furthermore, questions need to address not just the type of behaviour performed but also aspects such as the frequency, duration, intensity, and even social context in which it is performed. Where direct observation and/or objective measurement for example, taking blood or urine sample are not possible, researchers have to rely on self-report. When studies are interested in the frequency with which certain behaviour is performed, it is commonplace to ask study participants to complete a diary, for example of cigarettes/alcohol/foods consumed or activities undertaken. Participants in such studies are generally required to either record behaviour daily for a period of a week any longer places high demand on participants, or to reflect back on the previous week’s activity a retrospective diary ? RD. The latter has obvious memory demands ? could you accurately recall how many units of alcohol you drank seven days ago? While there is no evidence of a systematic bias towards overestimation or underestimation Maisto and Connors Shakeshaft et al. , some studies attempt to cross-validate behavioural self-reports by obtaining observer ratings or blood samples. A City Guide To Gaogou 2016.