Nunes, CéliaMoreira, Elsa E.Ferreira, Sandra S.Ferreira, DárioMexia, João T.2020-02-062020-02-062019http://hdl.handle.net/10400.6/9064When applying analysis of variance, the sample sizes may not be previously known, so it is more appropriate to consider them as realizations of random variables. A motivating example is the collection of observations during a fixed time span in a study comparing, for example, several pathologies of patients arriving at a hospital. This paper extends the theory of analysis of variance to those situations considering mixed effects models. We will assume that the occurrences of observations correspond to a counting process and the sample dimensions have Poisson distribution. The proposed approach is applied to a study of cancer patients.engRandom sample sizesMixedeffectsL extensions modelsF-testsCounting processesCancer registriesjournal article10.1080/02664763.2019.1641188