# Documentation

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# plotDiagnostics

Class: NonLinearModel

Plot diagnostics of nonlinear regression model

## Syntax

```plotDiagnostics(mdl) plotDiagnostics(mdl,plottype) h = plotDiagnostics(...) h = plotDiagnostics(mdl,plottype,Name,Value) ```

## Description

`plotDiagnostics(mdl)` plots diagnostics from the `mdl` linear model using leverage as the plot type.

`plotDiagnostics(mdl,plottype)` plots diagnostics in a plot of type `plottype`.

`h = plotDiagnostics(...)` returns handles to the lines in the plot.

`h = plotDiagnostics(mdl,plottype,Name,Value)` plots with additional options specified by one or more `Name,Value` pair arguments.

## Input Arguments

`mdl`

Nonlinear regression model, constructed by `fitnlm`.

`plottype`

Character vector specifying the type of plot:

 `'contour'` Residual vs. leverage with overlayed Cook's contours `'cookd'` Cook's distance `'leverage'` Leverage (diagonal of Hat matrix)

Default: `'leverage'`

### Name-Value Pair Arguments

Specify optional comma-separated pairs of `Name,Value` arguments. `Name` is the argument name and `Value` is the corresponding value. `Name` must appear inside single quotes (`' '`). You can specify several name and value pair arguments in any order as `Name1,Value1,...,NameN,ValueN`.

### Note

The plot property name-value pairs apply to the first returned handle `h(1)`.

 `'Color'` Color of the line or marker, a `ColorSpec` specification. For details, see `linespec`. `'LineStyle'` Type of line, a Line Properties specification. For details, see `linespec`. `'LineWidth'` Width of the line or edges of filled area, in points, a positive scalar. One point is 1/72 inch. Default: `0.5` `'MarkerEdgeColor'` Color of the marker or edge color for filled markers, a `ColorSpec` specification. For details, see `linespec`. `'MarkerFaceColor'` Color of the marker face for filled markers, a `ColorSpec` specification. For details, see `linespec`. `'MarkerSize'` Size of the marker in points, a strictly positive scalar. One point is 1/72 inch.

## Output Arguments

 `h` Vector of handles to lines or patches in the plot.

## Examples

expand all

Create a leverage plot of a fitted nonlinear model, and find the points with high leverage.

Load the reaction data and fit a model of the reaction rate as a function of reactants.

```load reaction mdl = fitnlm(reactants,rate,@hougen,[1 .05 .02 .1 2]);```

Create a leverage plot of the fitted model.

`plotDiagnostics(mdl)`

To examine the observation with high leverage, activate the Data Cursor and click the observation.

Alternatively, find the high-leverage observation at the command line.

`find(mdl.Diagnostics.Leverage > 0.8)`
```ans = 6```

expand all

## Tips

• For many plots, the Data Cursor tool in the figure window displays the x and y values for any data point, along with the observation name or number.

## References

[1] Neter, J., M. H. Kutner, C. J. Nachtsheim, and W. Wasserman. Applied Linear Statistical Models, Fourth Edition. Irwin, Chicago, 1996.