Numerical evaluation of cytologic data. XI. Nested designs in multivariate analysis of variance

Nested designs in multivariate analysis of variance allow the investigator to assess at what stages in an experimental procedure variability enters and to what extent. When employed in conjunction with a fixed-effects level in the design, a mixed model results, which provides the appropriate significance tests for the fixed-level effect; e.g., differences in cells between control patients and treated patients must be tested against the patient-to-patient variability, not against the cell-to-cell variability. A worked example for a three-level, mixed-model nested design is given, including the significance tests.