Define the different tasks of statistics.
Statistical tests are tools, appropriate for specific tasks. Tasks include summarizing a set of data with descriptive statistics, using difference tests to compare groups in experimental and quasi-experimental designs, and using relationship tests to see if two variables vary together systematically (relationship tests).
Select the correct statistical test.
Descriptive statistics summarize a set of numbers to describe an individual case or a sample of cases in terms of central tendency and/or variability. Difference tests are used when cases are sorted into groups on the basis of an explanatory variable. Relationship tests are used when there is one sample of cases and each case is measured on two variables to see if the variables covary.