Which of the following statements about good experiments is TRUE? A good experiment includes systematic variation for one or more hypothesized causal factors. A good experiment must have an experimental group. A control group may be useful but is not critical. A good experiment should include a potentially confounding factor in at least one group. A good experiment should only include replication if the hypothesis has never been tested before.
The Correct Answer and Explanation is:
Correct Answer:
A good experiment includes systematic variation for one or more hypothesized causal factors.
Explanation (300+ words):
In scientific research, a good experiment is carefully designed to test hypotheses by manipulating specific variables while controlling others to determine cause-and-effect relationships. The true statement among the options provided is: “A good experiment includes systematic variation for one or more hypothesized causal factors.” This means that the experiment deliberately changes (or varies) certain independent variables to observe their effect on dependent variables. This approach allows researchers to isolate the specific factor(s) they are testing and examine whether those factors actually influence the outcome.
This idea of systematic variation is at the heart of experimental design. For example, if a scientist wants to determine if a new fertilizer increases plant growth, the amount or type of fertilizer would be the causal factor that is systematically varied among different plant groups, while all other variables (like light, water, and soil type) are kept constant.
Now, let’s break down why the other options are not true:
- “A good experiment must have an experimental group.” — This is misleading. While experimental groups are often used, some experiments (like observational studies) may not have distinct experimental groups but can still yield valuable data. More importantly, an experiment doesn’t require a named “experimental group” if it’s using a different type of design.
- “A control group may be useful but is not critical.” — A control group is essential for comparison. Without it, it’s difficult to conclude whether the observed changes are due to the experimental treatment or other factors.
- “A good experiment should include a potentially confounding factor in at least one group.” — Confounding factors are variables that interfere with the results. Including them would compromise the validity of the experiment.
- “A good experiment should only include replication if the hypothesis has never been tested before.” — Replication is always important in experiments to ensure results are reliable and not due to chance.
In summary, systematically varying hypothesized causal factors while controlling others is central to good experimental design.