# Minitab Help 11: Influential Points

Minitab Help 11: Influential Points

## Influence 2 (outlier, low leverage, not influential)

• Create a basic scatterplot.
• Perform a linear regression analysis for all the data (click "Storage" in the regression dialog and select "Fits" to save the fitted values).
• Select Data > Subset Worksheet to create a worksheet that excludes observation #21 and Perform a linear regression analysis.
• Return to the original worksheet and select Calc > Calculator to calculate fitted values based on the fitted equation for the subsetted worksheet, e.g., FITX = 1.73+5.117*x.
• Return to the scatterplot and select Editor > Calc > Calculated Line with y=FITS and x=x to add a regression line to the scatterplot.
• Select Editor > Calc > Calculated Line with y=FITX and x=x to add a regression line based on the fitted equation for the subsetted worksheet.
• Click "Storage" in the regression dialog to calculate leverages, standardized residuals, studentized (deleted) residuals, DFFITS, and Cook's distances.

## Influence 3 (high leverage, not an outlier, not influential)

• Create a basic scatterplot.
• Perform a linear regression analysis for all the data (click "Storage" in the regression dialog and select "Fits" to save the fitted values).
• Select Data > Subset Worksheet to create a worksheet that excludes observation #21 and Perform a linear regression analysis.
• Return to the original worksheet and select Calc > Calculator to calculate fitted values based on the fitted equation for the subsetted worksheet, e.g., FITX = 1.73+5.117*x.
• Return to the scatterplot and select Editor > Calc > Calculated Line with y=FITS and x=x to add a regression line to the scatterplot.
• Select Editor > Calc > Calculated Line with y=FITX and x=x to add a regression line based on the fitted equation for the subsetted worksheet.
• Click "Storage" in the regression dialog to calculate leverages, DFFITS, and Cook's distances.

## Influence 4 (outlier, high leverage, influential)

• Create a basic scatterplot.
• Perform a linear regression analysis for all the data (click "Storage" in the regression dialog and select "Fits" to save the fitted values).
• Select Data > Subset Worksheet to create a worksheet that excludes observation #21 and Perform a linear regression analysis.
• Return to the original worksheet and select Calc > Calculator to calculate fitted values based on the fitted equation for the subsetted worksheet, e.g., FITX = 1.73+5.117*x.
• Return to the scatterplot and select Editor > Calc > Calculated Line with y=FITS and x=x to add a regression line to the scatterplot.
• Select Editor > Calc > Calculated Line with y=FITX and x=x to add a regression line based on the fitted equation for the subsetted worksheet.
• Click "Storage" in the regression dialog to calculate leverages, DFFITS, and Cook's distances.

## Hospital infection risk (two outliers, high leverages)

 [1] Link ↥ Has Tooltip/Popover Toggleable Visibility