Stimulus selection

Once the encoders have been selected for a judgment study, further selection must be made of precisely which aspects of the encoders' nonverbal behavior will serve as the stimulus materials for the judges. Suppose, for example, that we have selected as our encoders a group of classroom teachers who have been videotaped for thirty minutes on each of three different occasions. Suppose further that we have calculated that six minutes of videotape per teacher is all we will have time to show our judges, given the total number of teachers in our sample. How shall we select the six minutes from the ninety minutes?

Behavior sampling

We might decide that we should have a sample of teacher behavior from each of the three videotape recording occasions. Perhaps we will decide to choose the first forty seconds, the last forty seconds, and the midmost forty seconds of the behavior we are studying from each of the three occasions. In this sampling procedure, we will be sure to examine at least some of the behavior of the early, middle, and late periods of each of the occasions of observation. Although the particular selection of segments to be judged must depend on the particular purpose, it seems to be wise to sample systematically the various occasions of observation, the phases of each occasion of observation, and the types of specific behavior we want to present to our judges for evaluation.