To help you prepare for today's topic, carefully read these web pages and the assigned sections in Moore and Norusis. After completion of this project, you should be able to use SPSS to calculate basic descriptive statistics, including the mean, median, range, standard deviation, and quartiles for any variable. You should also be able to describe the relationships between these statistics, and how they are affected by data. These plots are useful in providing visual summaries of the scores obtained by subjects, and can be useful in getting a general sense of shape, center, and spread of scores observed on any given variable.
Descriptive statistics provide a convenient way of summarizing scores by using numbers.
For example, measures of center provide a way of determining which score is the most typical. Measures of spread provide a numeric value that summarizes how scores differ from each other, or from the most typical score. The most common measure used to summarize which score is most typical is the mean . Very simply, the mean is the arithmetic average of scores. The median is the score that divides the distribution into two equal halves.