A p-value of 0.05 indicates there is a 5% chance the observed result is due to chance.

A p-value of 0.05 indicates there is a 5% chance the observed result is due to chance.

• A. There is a 5% chance the result is due to chance
• B. The result is guaranteed to be true
• C. The sample size is 5% of the population
• D. The effect size is 0.05

Answer: (A)

The p-value gauges how compatible the observed data are with the idea that there is no real effect (the null hypothesis). If the p-value is 0.05, it means that, assuming the null hypothesis is true, there is a 5% chance of obtaining results as extreme as what was observed (or more extreme) just by random variation. In practice, this is the threshold researchers use to decide whether the data are unlikely enough under the null to call the result statistically significant at the conventional level. This interpretation is why the statement “there is a 5% chance the observed result is due to chance” is the best match. It captures the idea that the data could occur by chance under the null about 5% of the time. It does not imply that the result is guaranteed to be true, nor does it refer to the size of the population being studied, nor to how large or small the effect is. The p-value reflects the observed data under the null model, not the truth of the alternative, nor the practical importance of the effect.

The p-value gauges how compatible the observed data are with the idea that there is no real effect (the null hypothesis). If the p-value is 0.05, it means that, assuming the null hypothesis is true, there is a 5% chance of obtaining results as extreme as what was observed (or more extreme) just by random variation. In practice, this is the threshold researchers use to decide whether the data are unlikely enough under the null to call the result statistically significant at the conventional level.

This interpretation is why the statement “there is a 5% chance the observed result is due to chance” is the best match. It captures the idea that the data could occur by chance under the null about 5% of the time. It does not imply that the result is guaranteed to be true, nor does it refer to the size of the population being studied, nor to how large or small the effect is. The p-value reflects the observed data under the null model, not the truth of the alternative, nor the practical importance of the effect.