Deck 10 – Tests of Independence (LM9)

What does a chi-square contingency table test examine?

Whether two categorical variables are independent.

What is the Spearman rank correlation formula in terms of rank differences?

$r_s=1-\frac{6\sum d_i^2}{n(n^2-1)}$.

Why does the chi-square contingency table test count as a test of independence?

It compares observed counts with counts expected under independence.

Why does the Pearson correlation $t$-test use $df=n-2$?

Because the correlation test uses a $t$ distribution with $n-2$ degrees of freedom.