Parameter is a summary measure used to describe a group of people or objects that is based on data from all units in the group. Participant is a general term covering anyone who is involved in a research study and not just someone who is interviewed, eg in an observation study or a group discussion. Pearson Coefficient see product moment correlation coefficient. Perceptual Mapping is an analysis technique that is designed to demonstrate how consumers view a concept or brand relative to the alternatives. Perceptual maps can be constructed from different types of analysis, eg Factor analysis, correspondence analysis and multi-dimensional scaling.
Periodicity is a cyclical variation in a characteristic being measured.
Periodicity can lead to a bias in systematic sampling when the period of the cycle coincides with the sampling interval being used. Personal Observation is when human beings record the behaviour of interest or events taking place. Pictograph is a type of graph that uses pictures or symbols to display the data. Pilot Testing see pre-testing. Placement Test see home use test.