Observational methods: quantitative: quantified and systematic observations, frequency of behaviour, analysis of numbers. Measuring what: events: instantaneous and moment of onset (instantaneous, a behaviour can be considered as both. Define the boundaries: the concept of bout: where/when does it start and end (temporal and spatial boundaries, what happens with clusters of behaviours, acts, actions or events. Focal sampling: all occurrences of specified (inter)actions of an individual (or group) are recorded during each sampling period. Individual followed to whatever extent possible during each of his sample periods: keep in mind time of day and sampling period (rare behaviour may need large sampling behaviour) If studying older population, keep in mind they are not as active at certain times of the day. Scan sampling: observer records an individual"s current activity at preselected moments in time (fixed interval or random, can be used to obtain data from a large number of groups members by observing each in turn.