Stored model overview

Minitab automatically stores the last model that you fit for many of the linear model analyses. You can use these models to quickly and easily create graphs, make predictions, and optimize responses. Minitab automatically saves the following types of models:

Definitive screening design
Factorial design
General full factorial design
Analyze variability
Response surface designs
General linear model (GLM)
Mixed effects model
Regression
Binary logistic regression
Poisson regression

After Minitab stores a model, you can use the following analyses. These analyses become active when the active worksheet contains a stored model that satisfies the minimum requirements.

Analysis	Purpose	Minimum requirements
Predict	To predict the value of the response variable (fitted values) for the combinations of variable settings that you request	Any number and type of variables
Factorial Plots	To visualize the main effects and interaction effects	Any number and type of variables
Contour Plot	To show how the fitted response relates to two continuous variables with a two-dimensional view	Two or more continuous variables*
Surface Plot	To show how the fitted response relates to two continuous variables with a three-dimensional surface	Two or more continuous variables*
Cube Plot	To see the factors and combination of settings used in your design	A 2-level factorial design
Overlaid Contour Plot	To display contour plots for multiple responses in a single graph to visually identify an area where all of the responses are in a desirable range	Two or more continuous variables*
Response Optimizer	To identify the combination of input variable settings that jointly optimize a single response or a set of responses	Any number and type of variables*
Comparisons	To examine which factor level means are significantly different and to estimate by how much they are different.	You must have a general linear model or a mixed effects model

Mixed effects models do not produce contour plots, surface plots, cube plots, overlaid contour plots, or response optimizer plots.

Model details

After you fit a model for a response variable, an indicator appears in the bottom right corner of the column ID cell on the worksheet. A green indicator tells you that the model is up-to-date while a red indicator signifies an out-of-date model. A model is out-of-date when the data have changed since you fit the model. If you hover the pointer over the indicator, a tool tip appears that provides information about the model.

View Model sub-dialog box

Each model-based analysis has a View Model button in the main dialog box that you can click before you use the analysis. You can examine all of the models of the same type that are stored in the worksheet. You can only use an analysis if the model is both up-to-date and satisfies the minimum requirements.

View Model Used for Graph

Right-click the graph and choose View Model Used for Graph from the context menu to see which model created the graph. If a graph is out-of-date, it could be due to changes in the model, data, or worksheet since you created the graph.