Conduct a Lack of Fit Test
Conduct a Lack of Fit TestMinitab®
Procedure
- Select Stat >> Regression >> Regression ... >> Fit Regression Model ...
- Specify the response and the predictor(s).
- Minitab automatically recognizes replicates of data and produces the Lack of Fit test with Pure error by default.
- Select OK. The output will appear in the session window.
Example
The data set bluegills.txt contains the lengths (in mm) and ages (in years) of n = 78 bluegill fish. Is there sufficient evidence to conclude that there is a lack of linear fit between y = length and x = age of bluegill fish?
Minitab Dialog Box
Sample Output
Regression Analysis: length versus age
| Analysis of Variance | |||||
|---|---|---|---|---|---|
| Source | DF | Adj SS | Adj MS | F-value | P-value |
| Regression | 1 | 32966 | 32965.8 | 210.66 | 0.000 |
| age | 1 | 32966 | 32965.8 | 210.66 | 0.000 |
| Error | 76 | 11893 | 156.5 | ||
|
Lack-of-Fit |
4 | 3080 |
770.0 |
6.29 | 0.000 |
| Pure Error | 72 | 8813 | 122.4 | ||
| Total | 77 | 44859 | |||