1 Projectgroup Ethology and Socio-Ecology, Utrecht University, Utrecht, The Netherlands
2 Buro für Raumplanning und Informationsverarbeitung, Dortmund, Germany
PPEH is a program to detect patterns of change in sequential data. Data are assumed to be point events in chronological order. Time is split into intervals of fixed duration as defined by the user. The program presupposes a complete and continuous record of data extending over a defined length of time. The length of the sequences and the temporal resolution of the analysis can be adapted to the respective research question.
Within each continuous record the temporal positions of one event (the so-called target event) are registered in a relation to the occurrence of another (the criterion event), i.e. for each interval before (pre) or after (post) the criterion event the program determines wether the target event was observed.
The PPEH program is suited to evaluate the relative temporal distribution of events, for instance behaviors, within one individual, i.e. intra-individual sequences. It is particularly designed to analyze interaction sequences. To this end the temporal distribution of target events performed by one individual in relation to a criterion event performed by another is determined.
The results of the evaluation of several sequences are aggregated and the resulting frequency distribution of the target relative to the criterion is represented as a histogram. For inferential statistical testing a binominal test is employed to calculate the probability of observing a certain number of target events at a given time interval.