ABSTRACT
Interval-level variables are generally not suited to the types of analysis covered in Chapter 14. The techniques in Chapter 14 largely rely on variables having only a small number of categories. Interval-level variables frequently have a large number of different values. This chapter:
• explores techniques suitable to analysing interval variables without having to collapse these variables into a small number of categories;
• describes methods of analysis when the dependent variable is interval-level and the independent variable is categorical (comparison of means);
• describes the use of correlation coefficients when both the independent and dependent variables are interval-level (Pearson's correlation and rank-order correlation);
• introduces the analysis technique called regression analysis;
• outlines graphing methods and descriptive statistics suitable for interval-level variables;
• shows how to compare means to establish the existence of relationships;
• describes the use of tests of significance and interval estimates suitable for interval-level variables;
• provides a guide sheet to assist in selecting correlation coefficients discussed in Chapters 14 and 15.
