The best way to control extraneous variables in an experiment is to
A) subtract them from the results.
B) randomly assign subjects to conditions or groups.
C) ignore them.
The correct answer and explanation is:
Correct Answer: B) randomly assign subjects to conditions or groups.
Explanation (300 words):
In experimental research, extraneous variables are any variables other than the independent variable that might influence the dependent variable. If not controlled, these variables can introduce confounding effects, making it hard to determine whether the observed outcome was due to the treatment or another factor.
The best method to control these variables is random assignment. This means that each participant has an equal chance of being placed in any of the experimental groups. By doing this, researchers help ensure that extraneous variables are evenly distributed across all groups, minimizing their potential influence.
Let’s consider an example: Suppose researchers are testing a new teaching method and want to know if it improves student test scores. If all high-performing students are placed in the experimental group and low-performing students in the control group, the results could be biased. But if students are randomly assigned, both groups are likely to have a mix of high and low performers, making the results more valid and reliable.
Here’s why the other options are incorrect:
- A) Subtract them from the results: This is not practically possible unless the influence of every extraneous variable is known and quantifiable, which is rarely the case in real experiments.
- C) Ignore them: Ignoring extraneous variables can lead to invalid conclusions. Uncontrolled variables may affect the outcome, leading to confounded results.
Therefore, random assignment (B) is considered the gold standard in experimental design. It’s a fundamental part of internal validity, which refers to the degree to which an experiment correctly shows a cause-and-effect relationship between the independent and dependent variables.
By using random assignment, researchers reduce bias and make the experiment more trustworthy.