# Lesson 4: Two-Way Tables: Ordinal Data and Dependent Samples

Lesson 4 is divided into 2 parts. The first part deals with ordered classification. The second part deals with situations when the same sample is observed repeatedly.

Lesson 3 dealt with the concepts of independence and association in a two-way table with nominal classification. The test statistics introduced were Pearson and Likelihood chi-squares which do not take into account any ordering in the classification. To construct these test-statistics, if the ordering of the rows or columns in the table are interchanged, the value of the statistics do not change. When rows and/or columns of classification are ordered, more powerful tests exist and more information can be gleaned from the data structure using these tests.