What design principle is stressed for experiments or observational studies?

Choose the correct answer below.

A. Using dependent samples with paired data is generally better than using two independent samples.

B. When using paired data, keep the sample very small in order to keep the data manageable.

C. The methods for dependent samples can be used for any matched pairs.

D. Using two independent samples is the best choice for accurate results.

A). Using dependent samples with paired data is generally better than using two independent samples.

Explanation:

Observational studies is the research/study design in which the investigator observes the samples collected from the population in their natural pattern to make valid inferences without any kind of manipulation or interference. While the experimental studies involves a controlled or manipulated variable in order to check its impact over the independent variable and the relation between the two.

As per the question, the design principle that is emphasized for both the studies would be 'employing dependent samples along with the paired data is usually effective than employing two independent samples' as the former concerns one set of elements that makes them 'self-evident' (as the subjects of one sample can be employed to determine the subjects of other). Thus, option A is the correct answer.