ABSTRACT
First let us consider some hypothetical data collected in a naming task. A sample of 40 4-year-old children are presented with a series of 50 pictures depicting everyday objects. Their task is to name the objects represented in each picture, and the number of correctly named pictures is recorded for each child. The raw data are presented in Table 2.1. A useful way to organise these data would be to record the frequency of occurrence of each score in the data-set. In a frequency distribution table the scores are usually ranked from the lowest to the highest, and the number of occurrences of each score is given. Table 2.1 also includes the frequencies of the observed scores obtained by the sample of 4-year-old children in the naming task. The cumulative frequency and the percentage cumulative frequency of the scores are also given. The cumulative frequency of the scores is useful since it reveals the number of observations falling at or below (or above) a given score. The percentage cumulative frequency of the scores is also useful since it can be used to obtain the percentage of observations falling at or below a given score.
