Statistical Significance Statistics Example 1
Follow the full solution, then compare it with the other examples linked below.
Example 1
hardA drug trial finds a statistically significant reduction in blood pressure (). The mean reduction was 2 mmHg. Is this result practically significant?
Solution
- 1 Step 1: Statistical significance () means the reduction is unlikely due to chance alone.
- 2 Step 2: However, a 2 mmHg reduction is very small clinically — most doctors would not consider this meaningful.
- 3 Step 3: Statistical significance does not imply practical significance. Large samples can detect tiny differences that have no real-world importance.
Answer
Statistically significant but not practically significant — the effect size is too small to be clinically meaningful.
Statistical significance tells us whether an effect exists; practical significance tells us whether the effect matters. Both should be considered when interpreting results.
About Statistical Significance
A result is statistically significant when the p-value falls below a predetermined threshold (alpha, typically 0.05), indicating that the observed effect is unlikely to have occurred by random chance alone. Statistical significance is a binary decision criterion used in hypothesis testing — it does not measure the size or practical importance of the effect.
Learn more about Statistical Significance →More Statistical Significance Examples
Example 2 hard
Explain the difference between a Type I error and a Type II error in hypothesis testing.
Example 3 hardA study with 10,000 participants finds a statistically significant difference in test scores between
Example 4 hardA treatment improves average test scores by 12 points, but the p-value is 0.08. At [formula] is the