Question

1. roadwork can have a significant impact on wildlife. specifically, the mowing of areas adjacent to a road may affect the abundance of butterflies. to study the effect of mowing on the abundance of butterflies, researchers implemented two mowing strategies across 20 half - mile sections of roads in florida. for each half - mile section, one side of the road was randomly assigned to be mowed every six weeks, and the other side of the road was not mowed. at the end of three months, butterfly populations were estimated for each side of the road. which of the following is the best description of the study?

a) an experiment using a matched - pairs design
b) an experiment using a randomized placebo - controlled design
c) an experiment using a completely randomized design
d) a sample survey using cluster sampling
e) a sample survey using stratified sampling

Explanation:

• Matched - pairs design: In this study, for each half - mile section (a pair), one side (a unit in the pair) is mowed and the other (the other unit in the pair) is not mowed. The two sides of the same half - mile section are “matched” (they are adjacent and share many common environmental factors like proximity to the road, local climate etc.).
• Randomized placebo - controlled design: There is no placebo (a non - active treatment that looks like the real treatment) in this study. The treatments are mowing and non - mowing, not a treatment and a placebo.
• Completely randomized design: In a completely randomized design, experimental units (here, it would be the sides of the road) are randomly assigned to treatments without any prior matching. But here, the two sides of the same road section are related (matched).
• Sample survey: A sample survey is about collecting data by asking questions (usually through interviews or questionnaires). This is an experiment where a treatment (mowing) is imposed. Cluster sampling and stratified sampling are sampling methods for surveys, not for experiments.

Answer:

A. An experiment using a matched - pairs design