Two exact tests are presented for testing the hypothesis that the
residuals from a least squares regression are homoscedastic. The results
can be used to test the hypothesis that a linear [ratio] model explains
the relationship between variables as opposed to the alternative that
the ratio [linear] specification is correct. The first test is parametric and
uses the F-statistic. The second test is nonparametric and uses the
number of peaks in the ordered sequence of unsigned residuals. In conclusion,
the results of some experimental calculations of the powers of the tests are discussed.