Hypothesis Testing and
Tests of Association
Learning OutcomesAfter reading this chapter you will be able to:
• Understand the procedure of hypothesis testing. • Understand concepts of level of significance and degrees of freedom. • Decide appropriate measures of association/relationship. • Choose critical values from statistical tables. • Calculate measures of association—Chi-square statistic, rank correlation
and product-moment correlation.
• Conduct a test of significance for these measures and decide on the
strength of the relationship.
This chapter begins with explaining hypothesis testing and gives the essential steps used in conducting such a test. It looks at the relationship between variables and shows how to choose an appropriate measure of association or relationship between two variables. It then shows how to conduct a Chi-square test of association between two nominal measurements and gives an interpretation of the calculated value of the test statistic. Two further measures of correlation—Spearman's rank correlation and Pearson's product-moment correlation—are then explained and a test of significance of the relationships is shown with detailed calculations. The chapter finally explains how to choose an appropriate test for the type of measurements made.
We are often interested in investigating whether the data (sample estimates) that represent actual population values (generally called 'parameters') have changed