4. You are employed as a behavioural scientist at a substance rehabilitation
institution. You are tasked with a behaviour change intervention targeting
reckless drivers. You conduct an intervention in which two samples of ten
drivers are randomised to an experimental and a control group. Both groups
are asked to drive through a test circuit, and the number of errors made by each
member is recorded. The first group tackled the circuit sober, while the second
group tackled the circuit immediately after consuming two units of alcohol.
The results obtained are given in the following table:
NUMBER OF ERRORS
Group 1 (No Units Of Alcohol) Group 2 (Two Units Of Alcohol)
3 11
2 6
8 7
5 4
5 10
6 9
3 8
6 6
4 7
5 6
Perform an appropriate hypothesis test at the 5% significance level to
determine whether consumption of two units of alcohol has a significant
impact on driving ability, as measured by the number of errors made on a test
circuit. Show all calculations, both manually, and using MS Excel.
Include the following in your hypothesis test:
a. State the null and alternate hypotheses
b. State the design requirements and assumptions (assume assumptions
have been met)
c. State the decision rule
d. Calculate the value of the test statistic and make a decision
e. State the conclusion
f. Calculate and interpret effect size, if appropriate