Choosing the Right Word
A student writes in a lab report: "The results were very significant and showed a big difference between the groups." The teacher comments that "significant" is ambiguous in scientific writing, "very" and "big" are vague, and the report should distinguish statistical significance from practical importance. The student's data show a difference of 2% between groups, with a p-value of 0.03. The sample was large (n = 1,200). The student must revise the sentence to be precise without overstating the finding.
1. Revise the sentence and explain each change.
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Revised: "The difference between groups was statistically significant (p = 0.03) but small in magnitude (2 percentage points)." Changes: "significant" becomes "statistically significant" with the p-value supplied, removing ambiguity. "Very" is deleted because significance is not graded. "Big" becomes "small in magnitude" with the actual figure, which is honest-a 2% difference is statistically detectable with n = 1,200 but may not matter practically. The revision separates the two senses of importance the teacher flagged.
2. Why does sample size matter to the student's word choice?
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With a large sample, small differences can reach statistical significance, so "significant" alone would mislead a reader into assuming a large or important effect. Naming both the p-value and the effect size lets the reader judge practical relevance. Precision here is not pedantry; it prevents the report from overstating a modest finding.