複選題18. A researcher compares the average amount of daily screen time between teenagers and adults. Which of the following statements are correct? (A) The null hypothesis would state that there is a big difference in screen time between the two groups. (B) A very significant t-test result (p < 0.01) would suggest rejecting the null hypothesis. (C) A smaller confidence level would result in a wider confidence interval. (D) An F-test must be performed before the t-test to validate equal variances. (E) A high F value suggests the two groups have the very similar daily screen time with a lower Q value.