Final answer:
False, Marcus and Caroline will not have the same observed effect sizes when conducting the same hypothesis test with different random samples of the same population.
Step-by-step explanation:
The correct answer is b) False. If Marcus and Caroline take different random samples of the same population and conduct the same hypothesis test, they will not necessarily have the same observed effect sizes. The observed effect size is dependent on the specific sample that is taken, and since Marcus and Caroline took different samples, it is unlikely that they will obtain the exact same effect size. The sample size and other factors can also influence the observed effect size, but in this case, it is sufficient to know that taking different samples will generally lead to different observed effect sizes.