Question 2

This question concerns a study that was introduced in Assignment 2.

In a study concerning the effectiveness of Ginkgo biloba in treating tinnitus, 24 participants were recruited through advertisements in the national press in the United Kingdom. Once enrolled in the study, participants were asked to complete a number of questionnaires that allowed for the calculation of a severity of tinnitus score. Participants were then instructed to take three tablets a day (each containing 50mg of Ginkgo biloba) over a 12 week period. After this time participants completed the same questionnaires so that their severity of tinnitus could again be calculated. All participants are assumed to have complied with the treatment regimen.

(a) If the mean severity of tinnitus score for patients at entry to the study was found to be 30.07 units (with a standard deviation of 6.10 units) and after the 12 week period was found to be 27.26 units (with a standard deviation of 5.20 units), using a Type 1 error level of 0.05 (i.e. a = 0.05), determine if there is a “statistically significant” difference in mean score before and after treatment. State the appropriate null and alternative hypotheses, and show all working. 

[Note: if needed, the standard deviation of the differences (score at entry to study – score after treatment) was 7.10 units.]

(b) State and justify your conclusion clearly so that an individual without your statistical knowledge could understand the results.

Remember to show your working and justify your conclusions.