Which statement best describes external validity in rodent research?

• A. External validity concerns whether findings apply to the same animals used in the study.
• B. External validity measures statistical significance within the sample.
• C. External validity concerns generalizability of findings to other populations or settings.
• D. External validity relates to the reliability of measurements.

Answer: (C)

External validity is about whether what you observe in your rodent study would hold true in other populations or practical settings beyond the exact animals and conditions used in the experiment. In rodent research, this means asking if the results generalize to different strains, ages, sexes, vendors, housing conditions, handling methods, diets, or even different labs and species. For example, if a treatment reduces a certain behavior in one strain of mice housed under standard lab conditions, external validity concerns whether the same effect would be seen in another strain, in female mice, in rats, or in mice housed with enrichment. This focus on generalizability across contexts is what makes the statement describing external validity the best choice. The other aspects—statistical significance within the sample, reliability of measurements, or internal control of confounds—address different facets of a study and do not capture generalizability to broader settings.