12   Question 3 continued _____________________________________________________________________________________ _____________________________________________________________________________________ _____________________________________________________________________________________ _____________________________________________________________________________________ _____________________________________________________________________________________ _____________________________________________________________________________________ _____________________________________________________________________________________ _____________________________________________________________________________________ There is an assumption about variance that is necessary for the t‑test in (c) to be valid. (d) State the assumption about variance, in context, and comment on its appropriateness, given the data in Figure 4. (2) _____________________________________________________________________________________ _____________________________________________________________________________________ _____________________________________________________________________________________ _____________________________________________________________________________________ _____________________________________________________________________________________ _____________________________________________________________________________________ _____________________________________________________________________________________ _____________________________________________________________________________________ _____________________________________________________________________________________ _____________________________________________________________________________________ _____________________________________________________________________________________ Turn over 13   Question 3 continued Klazine’s colleague, Aurora, is concerned that the sample sizes used in their study are too small to be able to detect a difference between the two groups of children. (e) Discuss Aurora’s concern about sample sizes. Include one reference to the statistical techniques applied in (a) and in (c) and their conclusions and one reference to the effect of increasing sample sizes. (2) _____________________________________________________________________________________ _____________________________________________________________________________________ _____________________________________________________________________________________ _____________________________________________________________________________________ _____________________________________________________________________________________ _____________________________________________________________________________________ _____________________________________________________________________________________ _____________________________________________________________________________________ _____________________________________________________________________________________ _____________________________________________________________________________________ _____________________________________________________________________________________ _____________________________________________________________________________________ _____________________________________________________________________________________ (f) If Klazine uses a much larger sample of children in her study, what effect would you expect this to have on the confidence intervals in (a) and in (b)? (1) _____________________________________________________________________________________ _____________________________________________________________________________________ _____________________________________________________________________________________ _____________________________________________________________________________________ _____________________________________________________________________________________ _____________________________________________________________________________________ (Total for Question 3 is 19 marks)