I’m having trouble calculating this repeated measures ANOVA. Please help! 2. a.

Question

I’m having trouble calculating this repeated measures ANOVA. Please help! 2. a. A manufacturing company is concerned about the effect of fatigue on the speed with which its workers can assemble pocket calculators. For10 workers, the average time (in seconds) it takes to assemble a pocket calculator is measured at the beginning, in the middle, and at the end of the shift. Does performance change across periods of the workers' shift? Use alpha.01. Repeated measures Worker Beginning Middle End A 20 B 28 C 22 21 23 30 31 23 24

Explanation / Answer

Here we have data from 10 different workers and we need to check if there is significant difference between begining, middle and end observations. One way ANOVA is best analysis method in this case and we should not perform repeated meaures ANOVA.

Excel output for one way ANOVA is as follows:

Observe that the p-value for significance of ANOVA model is 0.2896 > 0.01 hence we failed to reject the null hypothesis of no difference and conclude that there is significant difference between the three shifts.

b) Yes, we should perform pairwise comparison to check exactly which shifts differ significantly. In order to do this, one should perform Post-HOC tests.

Anova: Single Factor SUMMARY Groups Count Sum Average Variance Biginning 10 221 22.1 10.54444 Middle 10 231 23.1 14.54444 End 10 247 24.7 14.67778 ANOVA Source of Variation SS df MS F P-value F crit Between Groups 34.4 2 17.2 1.297569 0.289692 5.488118 Within Groups 357.9 27 13.25556 Total 392.3 29

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