Final answer:
In a randomized block design experiment, treatments and control groups are assigned randomly within divided groups to control for confounding variables. The correct answer is option (b).
Step-by-step explanation:
In a randomized block design experiment, the true statement regarding its methodology is the following: random allocation of treatment and control groups is done within the divided groups. This approach is taken to control for the effects of potential confounding variables, which are known as blocks.
In such experiments, participants are not selected at regular intervals out of the population, nor is the total population randomly divided into groups of equal size with a treatment assigned to each group. Instead, participants are first divided into homogeneous blocks based on certain characteristics, and then within each block, they are randomly assigned to treatment or control groups. This ensures that the potential confounding variables are evenly distributed across each treatment group, thus minimizing their impact on the results.
The purpose of using a randomized block design is to increase the statistical power of the experiment by reducing the variability caused by the confounding variables. Hence, the correct option for this question is (b.) random allocation of treatment and control groups is done within the divided groups.