An efficiency expert wants to determine whether the time an assembly worker requ

Question

An efficiency expert wants to determine whether the time an assembly worker requires to perform a standard task might be related to 1) number of years on the job, 2) the score on a pre-employment aptitude test, and 3) the shift they are working.

The data collected is in the file Employees.xlsx.

Assuming all other variables are the same, how much faster is the afternoon shift worker than the morning shift worker? Please highlight your answer.

Time Years TestScore Shift 52 7 73 Morning 48 14 78 Morning 56 8 71 Night 52 6 75 Morning 48 10 78 Afternoon 45 6 78 Afternoon 42 10 80 Afternoon 51 11 72 Night 51 10 79 Night 53 6 77 Night 47 8 79 Morning 45 12 84 Afternoon 49 12 72 Afternoon

Explanation / Answer

LM=lm(Time~Years+ TestScore+ factor( Shift), data=data)
> summary(LM)

Call:
lm(formula = Time ~ Years + TestScore + factor(Shift), data = data)

Residuals:
Min 1Q Median 3Q Max
-3.0760 -1.6320 0.4842 1.2206 2.0715

Coefficients:
Estimate Std. Error t value Pr(>|t|)
(Intercept) 82.9649 13.7917 6.016 0.000318 ***
Years -0.1686 0.2393 -0.705 0.500980
TestScore -0.4525 0.1764 -2.566 0.033331 *
factor(Shift)Morning 2.7663 1.4760 1.874 0.097771 .
factor(Shift)Night 5.0875 1.5592 3.263 0.011476 *
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Signif. codes: 0 ‘***’ 0.001 ‘**’ 0.01 ‘*’ 0.05 ‘.’ 0.1 ‘ ’ 1

Residual standard error: 2.093 on 8 degrees of freedom
Multiple R-squared: 0.8028, Adjusted R-squared: 0.7042
F-statistic: 8.142 on 4 and 8 DF, p-value: 0.006369

Conclusion: The estimated p-value of year variable is 0.5010. Hence, it does not have the significant effect on Time at on 0.05 level of significance. The p-value of the Test score is 0.0333. Hence, it has the significant effect on Time at on 0.05 level of significance.

For shift, Afternoon is considered as a reference, the p-value of the morning is 0.0978. Hence, morning shift does not have the significant difference from the afternoon at 0.05 level of significance.

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