ABSTRACT
In the mind of the layman the field of statistics is normally associated with the collection of great volumes of numerical information which is subsequently tabulated, charted and summarized in various ways. Hence we learn of the ‘average number of children in a British family’, or the ‘median wage of industrial workers in south-east England’. To be sure, the use of statistics to describe large collections of numerical information is perfectly legitimate. Indeed the psychologist takes over these methods of description when presenting the results of his experiments, as we saw in the last chapter. But we also use statistics in a much more fundamental way to draw inferences from the results of an experiment. We don’t simply want to report the scores of our two groups of subjects, or to give the mean and standard deviation and leave it at that. We want to use the data to test our original prediction-to decide whether the independent variable is having the effect we supposed, or whether, perhaps, there is no real difference between the performance of the two groups. This is the function of inferential statistics.
