Problems in fitting a cosine curve.
In fitting of cosine curves latent experimental inequalities due to a serial effect have to be excluded. Though cosinor analysis may be sufficient then, inclusion of biological time, i.e. not fitting values to time but to a function of time, will lead to further improvement.
D000818:Animals; D001699:Biometry; D002467:Cell Nucleus / Q000648:ultrastructure; D002940:Circadian Rhythm; D008099:Liver / Q000033:anatomy & histology; D008297:Male; D051381:Rats