Analysis of data from multiclinic experiments

The analysis of data from multiclinic experiments is put in the framework of a mixed model in which the treatment effects are assumed to be fixed, and clinic and clinic by treatment effects are assumed to be random. The analysis in the unbalanced case is developed under the usual mixed model assumptions. The maximum likelihood estimates and likelihood ratio tests of the parameters are derived following the approach of Hemmerle and Hartley (1973). The T2 test is shown to be asymptotically equivalent to the analysis of variance F test in the balanced case. The distribution of the test statistic in the case of proportional cell frequencies is also discussed. Some investigation is made of the distribution of the test statistic by applying the method of Box (1954).