In: Statistics and Probability
chi square test of independence helps us to find whether 2 or more attributes are associated or not.e.g. whether playing chess helps boost the child's math or not. It is not a measure of the degree of relationship between the attributes. it only tells us whether two principles of classification are significantly related or not, without reference to any assumptions concerning the form of relationship.
chi square test of homogeneity is an extension of chi square test of independence...tests of homogeneity are useful to determine whether 2 or more independent random samples are drawn from the same population or from different populations. instead of one sample- as we use with independence problem, here we have two or more samples.
Both the types of tests are concerned with cross classified
data. both use the same testing statistics. However they are
different from each other.
Test for independence is concerned with whether one attribute is
independent of the other and involves a single sample from the
population.
On the other hand, test of homogeneity tests whether different
samples come from same population. It involves 2 or more
independent samples-one from each of the populations in
question.