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Select the graphs to display for Stability Study

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Stat > Regression > Stability Study > Stability Study > Graphs

The graphs you can display depend on whether you have a batch factor, and whether the batch factor is fixed or random.

In This Topic

No batch factor

Shelf life plot
Display the shelf life plot, which shows the linear change in the response over time.
Residuals for Plots
Specify the type of residuals to display on the residual plots. For more information, go to Which types of residuals are included in Minitab?.
  • Regular: Plot the regular raw residuals.
  • Standardized: Plot the standardized residuals.
  • Deleted: Plot the Studentized deleted residuals.
Residual Plots
Use residual plots to examine whether your model meets the assumptions of the analysis. For more information, go to Residual plots in Minitab.
  • Individual plots: Select the residual plots that you want to display.
    Histogram of residuals
    Display a histogram of the residuals.
    Normal probability plot of residuals
    Display a normal probability plot of the residuals.
    Residuals versus fits
    Display the residuals versus the fitted values.
    Residuals versus order
    Display the residuals versus the order of the data. The row number for each data point is shown on the x-axis.
  • Four in one: Display all four residual plots together in one graph.
Residuals versus the variables
Enter one or more variables to plot versus the residuals. You can plot the following types of variables:
  • Variables that are already in the current model, to look for curvature in the residuals.
  • Important variables that are not in the current model, to determine whether they are related to the response.

Fixed batch factor

Shelf life plot
Display shelf life plots, which show the linear change in the response over time. If batch is a fixed factor and is included in the final model, then you can specify how many batches to show on the combined plot and whether to show individual plots for each batch.
Combined plots
  • No combined graph: Do not display plots that show multiple batches.
  • Combined graph for all batches: Display all the batches on a single plot.
  • Combined graphs with 4 batches per graph: Display no more than 4 batches on each plot. For example, if you have 12 batches, Minitab displays 3 plots that each show 4 batches.
Individual plots
  • No graphs for individual batches: Do not display a separate shelf life plot for each batch.
  • Graphs for individual batches: Display a separate shelf like plot for each batch.
Residuals for Plots
Specify the type of residuals to display on the residual plots. For more information, go to Which types of residuals are included in Minitab?.
  • Regular: Plot the regular raw residuals.
  • Standardized: Plot the standardized residuals.
  • Deleted: Plot the Studentized deleted residuals.
Residual Plots
Use residual plots to examine whether your model meets the assumptions of the analysis. For more information, go to Residual plots in Minitab.
  • Individual plots: Select the residual plots that you want to display.
    Histogram of residuals
    Display a histogram of the residuals.
    Normal probability plot of residuals
    Display a normal probability plot of the residuals.
    Residuals versus fits
    Display the residuals versus the fitted values.
    Residuals versus order
    Display the residuals versus the order of the data. The row number for each data point is shown on the x-axis.
  • Four in one: Display all four residual plots together in one graph.
Residuals versus the variables
Enter one or more variables to plot versus the residuals. You can plot the following types of variables:
  • Variables that are already in the current model, to look for curvature in the residuals.
  • Important variables that are not in the current model, to determine whether they are related to the response.

Random batch factor

Shelf life plot
Display the shelf life plot, which shows the linear change in the response over time.
Residuals for plots
You can specify the type of residual to display on the residual plots. For a stability study with a random batch factor, you can select marginal or conditional residuals. For more information, go to Marginal fits and residuals versus conditional fits and residuals.
  • Marginal regular: Marginal residuals are the difference between the fits and the observed values for a randomly-selected batch from the population. Use the marginal residuals to describe the error of the predictions for new batches.
  • Marginal standardized: Plot the standardized versions of the marginal residuals. If an observation has a standardized residual greater than 2, it may be an outlier in your data.
  • Conditional regular: Conditional residuals are the difference between the fits and the observed values for the batches in the sample data. Use the conditional residuals to check the normality of the residuals.
  • Conditional standardized: Plot the standardized versions of the conditional residuals. If an observation has a standardized residual greater than 2, it may be an outlier in your data.
Residual Plots
Use residual plots to examine whether your model meets the assumptions of the analysis. For more information, go to Residual plots in Minitab.
  • Individual plots: Select the residual plots that you want to display.
    Histogram of residuals
    Display a histogram of the residuals.
    Normal probability plot of residuals
    Display a normal probability plot of the residuals.
    Residuals versus fits
    Display the residuals versus the fitted values.
    Residuals versus order
    Display the residuals versus the order of the data. The row number for each data point is shown on the x-axis.
  • Four in one: Display all four residual plots together in one graph.
Residuals versus the variables
Enter one or more variables to plot versus the residuals. You can plot the following types of variables:
  • Variables that are already in the current model, to look for curvature in the residuals.
  • Important variables that are not in the current model, to determine whether they are related to the response.
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