Final answer:
The best illustration of the distinction between statistical significance and practical importance is a small p-value indicating a very unlikely occurrence if the null hypothesis is true. Practical importance goes beyond statistical significance and considers the magnitude or effect size of the observed difference.
Step-by-step explanation:
The best illustration of the distinction between statistical significance and practical importance is a) a small p-value.
In statistical hypothesis testing, a small p-value indicates that the observed data is very unlikely to occur if the null hypothesis is true. This provides strong evidence to reject the null hypothesis in favor of the alternative hypothesis. However, practical importance goes beyond statistical significance and considers the magnitude or effect size of the observed difference. A large effect size, as indicated by b) a large effect size, is an important factor in determining practical importance. It shows that the observed difference between groups or variables is substantial and has real-world significance, regardless of the statistical significance.