Question

what does it mean if the results of a study are statistically significant?
a. the null hypothesis can never be rejected in future studies.
b. the study needs to be redesigned and conducted again.
c. the observed effect is unlikely to have occurred by chance, according to the significance level.
d. the sample size was too small to reach a valid conclusion.

Explanation:

Statistical significance means that the probability of the observed result occurring by chance (assuming the null hypothesis is true) is very low (below the significance level, often 0.05). Option a is incorrect as future studies can still reject or not reject the null hypothesis. Option b is wrong as statistically significant results don't imply a need for redesign. Option d is incorrect as statistical significance takes sample size into account (e.g., in calculating test - statistics like t - tests or z - tests).

Answer:

C. The observed effect is unlikely to have occurred by chance, according to the significance level.