Worked example: Random allocation to treatment group
Suppose that you were interested in the effects of a drug on reaction times to approach a stimulus. Your hypothesis is that your drug will affect reaction times in a dose-dependent manner.
- The fist thing to do is to choose the sample population. Try to choose your sample from as many populations as you can to increase variability (this will help to equalize between- and within-group variance which is particularly useful if your effect size is likely to be small).
- Next, choose an equal number of animals from each of the populations, sex match them, and allocate them to each of your treatment groups
- Finally, organise your housing cages by allocating animals that are from different populations and treatment groups to each cage.