Final answer:
The null standard error is a measure of statistical significance and indicates no significant difference.
Step-by-step explanation:
The correct interpretations of the null standard error are:
- A. A measure of statistical significance: The null standard error is used to calculate the margin of error for hypothesis testing, determining if results are statistically significant.
- C. Indicates no significant difference: A null standard error equal to zero suggests that there is no significant difference between the groups being compared.