The Mood's Median Test is a nonparametric test of the equality of medians for two or more populations. Its parametric counterpart is the One-Way Analysis of Variance.
This procedure assumes that the samples are randomly and independently drawn from populations that have the same shape. It is more robust than the Kruskal-Wallis for data with outliers and is appropriate for preliminary stages of analysis.
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Null Hypothesis, H0 |
Alternate Hypothesis, H1 |
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m1 = m2 = . . . = mi |
m1 ¹ m2 ¹ . . . ¹ mi |
where mi are the medians of population i.
1. Choose ProcessMA > Statistics > Nonparametric > Mood’s Median Test.
2. In Data in, choose how your data is stored.
· If your data in stored in a single column:
- In Variable, select the column containing the response.
- In Category, select the column containing subgroup codes.
· If your data in stored in different columns:
- In Variables, select the columns containing the separate responses.
3. Click OK.
Optional
4. Check Plot confidence interval, if you want to display the confidence intervals for the medians.
Note To select a column of data into a textbox, double-click on any of the column names shown in the list on the left of the dialog box while in the textbox.
Variable: Numeric.
Category: Text or Numeric; Must have the same number of data points as the Variable; Must contain at least 2 distinct categories.
Variables: Numeric.
You are the manager of the mortgage department in a bank. You have three officers processing mortgage applications. You collected data on cycle time to process applications for the last 2 months and you want to assess if the three officers have the same processing speed.
1. Open worksheet ProcessMA > Tools > Data Files > Stat.xls.
2. Choose ProcessMA > Statistics > Nonparametric > Mood’s Median Test.
3. In Data in, choose a single column.
4. In Variable, select Y – Cycle time.
5. In Category, select Z – Officer.
6. Check Plot confidence interval.
7. Click OK.
Interpretation
For a desired a = 0.05, since p = 0 < a, we will reject H0. Therefore, we conclude that there is no significant evidence that the median cycle times for the three officers are different.