Which of these statements best describes a matched-pair design?
a.) A design in which an entire sample is divided into pairs, and then the pairs are matched together at random.
b.) A design in which only two treatments are tested on pairs of similar subjects.
c.) A design in which the total population is divided into homogeneous blocks and a treatment is assigned to every element of the block.
d.) A design in which the total population is randomly divided into groups of equal size and a treatment is assigned to each group.
The correct answer and explanation is :
The correct answer is:
b.) A design in which only two treatments are tested on pairs of similar subjects.
Explanation:
A matched-pair design is a type of experimental design used in statistics to compare two treatments while minimizing variability due to confounding factors. This design is particularly useful when the response variable is influenced by multiple factors, and the goal is to control for these factors as much as possible.
In a matched-pair design, subjects are grouped into pairs based on similar characteristics that could affect the outcome of the study. These characteristics may include age, gender, health status, or other relevant variables. Each pair consists of two subjects who are as similar as possible. One member of each pair is randomly assigned to receive one treatment, while the other member receives the alternative treatment. In some cases, instead of using two different subjects in a pair, a single subject can serve as their own control by receiving both treatments at different times in a randomized order (this is known as a within-subjects design).
This design is particularly useful because it reduces variability between subjects, making it easier to detect differences caused by the treatments rather than differences between individuals. By controlling for confounding factors within pairs, matched-pair designs increase the statistical power of an experiment, allowing researchers to draw more reliable conclusions.
For example, if a researcher wants to compare the effectiveness of two pain relief medications, they could match subjects based on age and severity of pain. One person in each pair would receive Drug A, while the other receives Drug B. The difference in pain relief between the two treatments within each pair is then analyzed, reducing the influence of external factors.
In contrast, the other answer choices describe different experimental designs, such as randomized block designs or completely randomized designs, which do not focus on pairing subjects.