For 'lmcal' models this function performs four tests: two ANOVAs
between linear and quadratic model, without and with log-log transform
(first is mentioned in literature as Mandel's fitting test), and
two ANOVAs comparing four polynomial models, weighted and unweighted.
For 'nlscal' models two ANOVAs are performed - between asymptotic
models without and with intercept term, and between three and four
parameter logistic models.