Review Descriptive Statistics - Quick Tab

Select the Quick tab of the Review Descriptive Statistics dialog box to access options to review the most commonly requested descriptive statistics on the previously selected variables (items).

Means & standard deviations. Click the Means & standard deviations button to display a spreadsheet containing means and standard deviations for all items in the scale. By default the standard deviation is computed as the square root of the sum of squared deviations about the mean (SS) divided by N - 1. The resulting statistic is an estimate of the population Sigma (this statistic can then be used to draw inferences about the population from which the sample was drawn).

A particularly useful Graph of Input Data for this spreadsheet is a histogram (frequency distribution) of the selected variable, with the normal distribution superimposed. This plot can be beneficial as a quick check of whether the assumption of normality has been violated (on which the computation of the correlation coefficients is based, see Basic Statistics).

Correlations. Click the Correlations button to display a spreadsheet containing either tetrachoric correlations or Pearson-product moment correlations, according to the Correlation matrix selected via the Reliability and Item Analysis Startup Panel - Advanced tab. A particularly useful Graph of Input Data for this spreadsheet is a scatterplot of the respective correlation coefficients. The plot will indicate the regression line as well as the 95% confidence limits for the regression line.