Plot the binormal-predicted ROC curve with provided parameters

## Arguments

- a
vector: the mean(s) of the diseased distribution(s).

- b
vector: the standard deviations(s) of the diseased distribution(s).

## Value

A ggplot2 object of the plotted ROC curve(s) are returned.
Use `print`

function to display the saved object.

## Details

`a`

and `b`

must have the same length. The predicted ROC curve
for each `a`

and `b`

pair will be plotted.

## Examples

```
binormalPlot <- PlotBinormalFit(c(1, 2), c(0.5, 0.5))
## print(binormalPlot)
```