A group of sports psychologists is interested in nding out whether a new technique that they've developed will help older orienteers to maintain a positive mental attitude while competing, and hence will improve their performance in the long term. The sports psychologists decide to run a trial in which they teach their technique to a sample of older orienteers. They intend to select a group of orienteers to whom they will teach the technique, and will also select another group that they will just monitor.

(a) What design of clinical trial best describes the study that the sports psychologists intend to set up?

(b) One of the variables that the sports psychologists will measure is the time taken for each orienteer to go round a particular orienteering course.

(i) Give a reason why this variable could be regarded as objective data.

(ii) Give a reason why this variable would be regarded as interval scale data.

(c) Suggest a hypothesis test that could be used to analyse the data described in part (b) to investigate whether there is evidence that the psychological test improves performance. Give a reason why this test might turn out to be unsuitable.