Plots discrimination index, as calculated using the `"conventional"`

formula, or via `"PBCC"`

, against difficulty index. Several parameters
control settings related to the appearance of the final plot.

plotDiscriminationDifficulty(mctd, type = "conventional",
show_labels = TRUE, hide_legend = TRUE, show_guidelines = TRUE,
show_gridlines = TRUE, max_limits = "max_x")

## Arguments

mctd |
Existing mcTestAnalysis data object |

type |
One of `"conventional"` , `"pbcc"` , or
`"pbcc_modified"` |

show_labels |
Should the question number be shown next to points? If
ggrepel is installed it will be used to ensure that all point labels
are legible on the plot. |

hide_legend |
Should the plot legend be hidden? |

show_guidelines |
Should recomended discrimination or difficulty indice
ranges be shown on the plot as a dotted line? |

show_gridlines |
Should the plot include gridlines? |

max_limits |
Set x- and y-axis limits. One of `"max_x"` (x
positive, y free), `"max_y"` (x free, y positive), `"max_y+"` (x
free, y in [-1,1]), `"max_all+"` (x positive, y positive),
`"max_all"` (x positive, y in [-1,1]), and `NULL` (all free). |