What is the difference between the F-Test and the Chi Square Test?
You use a chi-square test to compare the standard deviation (or variance) of a population to a given (i.e., constant) value; is has one degree of freedom value (based on the sample size for given population).
You use an F-test to compare the variances of two populations to each other; it has two degree of freedom values (based on each of the sample sizes for the two populations).