The president of Meadwestvaco wants to know when (morning, afternoon or evening) her shipping employees are most efficient (in terms of time) in packing and loading trucks for transport. She has the same group of employees work the three different shifts during alternating weeks for four months, measuring their output in terms of weight at the end of each week. What statistical test should she use to get his answer?
The correct answer and explanation is :
The president of MeadWestvaco should use a repeated measures ANOVA (Analysis of Variance) to analyze the data and determine when the shipping employees are most efficient.
Explanation:
A repeated measures ANOVA is appropriate because:
- Same Employees Across Shifts: The same group of employees works all three shifts (morning, afternoon, and evening) in different weeks, meaning the data is dependent (i.e., repeated measures).
- Multiple Time Points: Each employee’s performance is measured multiple times over the four-month period, making this a within-subjects design.
- Comparing More Than Two Conditions: Since we have three different shifts (morning, afternoon, and evening), we need a test that can compare multiple conditions rather than just two.
Why Not Other Tests?
- Independent Samples t-test: This test compares only two groups at a time and assumes different participants for each group, which is not the case here.
- One-Way ANOVA: A standard one-way ANOVA is used for independent groups, but in this case, each employee is measured under all three conditions, making a repeated measures design necessary.
- Paired t-test: This is used for two related conditions, but since there are three conditions (shifts), a repeated measures ANOVA is more appropriate.
How It Works:
The repeated measures ANOVA will test whether there is a statistically significant difference in shipping efficiency across the three shifts. If a significant difference is found, a post-hoc test (like Bonferroni or Tukey) can determine which shifts differ from each other.
By using this test, the president can make informed scheduling decisions based on when employees perform best.