For analysis the effects of different concentrations of Natamycin on some physicochemical and microbial properties of yogurt, yogurt samples were preserved by addition of Natamycin at 6 different concentrations. Then the properties were measured in 4 different points of time (on weekly basis).
Which method is preferred to analysis the data? Is it possible to use one way anova ignoring the time (i.e do analysis for each point of time separately), or it should be analysis using repeated measure?

It should be note that after measuring each sample properties it throw away! I mean the measures are not repeated on the same sample during the time but on the samples with the same level of treatment.


1 Answer 1


Based on the last paragraph, there is no repeated measurement. You mentioned one way ANOVA, I assumed your data is suitable for linear model.

Then you can put both concentration and time into model as covariates. If you treat them as categorical variables, it is two way ANOVA. If one of them as continuous and another as categorical, it is ANCOVA. You can also treat both of them as continuous. You can also add the interaction term into the model. All of this model may be more powerful than separated one way ANOVA.


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