Week 9 Lecture SWIN BUR NE SWINBURNE UNIVERSITY OF TECHNOLOGY STA10003 FOUNDATIONS OF STATISTICS Sandra Wyatt KNOW ING 1 Revision of Week 8 · Paired samples t-test · Used to compare the means of two measurements: - Police trainees are able to correctly identify more license plate numbers after a memory training course than before undertaking the course. - Children aged between 12 and 16 years overestimate their self-reported heights. - Greyhounds trained using 'live' lures complete a time trial faster ... KNOW ING 3 1
Revision of Week 8 Researchers are interested in the time spent on household chores. They hypothesise that people spend more time preparing meals than they spend doing dishes. In order to investigate this, they take a random sample of 100 Australian adults and ask them to keep a detailed diary of their daily activities for a week. Researchers then recorded the time spent preparing meals and the time spent doing dishes for each participant. KNOW ING 4 Revision of Week 8 a. What is the alternative hypothesis in terms of the researcher's expectations? b. What sort of experimental design has been used to collect the data? Independent groups / Matched Pairs /Repeated Measures c. Which hypothesis test would we need to produce to test the researchers' hypothesis? d. Which order should we enter the data? KNOW ING 5 2
Revision of Week 8 · Assumptions: V Independence: I Random selection of Australian adults V Normality: - Population of the difference scores is approximately normally distributed DIFF_Time Revision of Week 8 Paired Samples Statistics Pair 1 Time spent preparing meals last week [mins] Time spent doing dishes last week [mins] Mean N 356.3005 304.6864 100 120.54198 Std. Deviation 100 108.83591 10.88359 KNOW ING 6 Std. Error Mean Std. 12.05420 Paired Samples Test Paired Differences Std. Std. Error Mean Deviation Mean 95% Confidence Interval of the Difference Lower t df Upper Pair 1 Time spent preparing meals last week [mins] - Time spent doing dishes last week [mins] 51.61404 67.53675 6.75368 38.21328 65.01479 7.642 Sig. (2-tailed) 99 .000 e. Is the researchers' hypothesis supported? f. Interpret the 95% confidence interval for the difference. g. Write a report on these results. KNOW ING 7 3