In order to establish a statistical correlation between a and E, we need to compare two groups that are basically the same, except that a is present in one and not present in the other.Given that the individual members of these groups might vary quite a lot, how can we make it likely that, apart from the presence of a, the two groups are basically the same?

Question

Quizplus · Accepted Answer

Using large, randomly chosen groups increases the likelihood that the two groups will be similar apart from the variable being studied (in this case, a). This helps to reduce the impact of individual differences within each group, and increases the chances of obtaining meaningful information about the correlation between a and E. Small randomly chosen groups may not be representative enough and matching individuals in both groups would not account for unknown confounding factors. Option E is incorrect because it is possible to create similar groups even though there may be some variability within the groups.

In Order to Establish a Statistical Correlation Between a and E