Entropy_plot | R Documentation |

Item the value of the entropy curve at a point `theta`

is the expected
value of the surprisal curve values. Entropy is a measure of the randomness
of the surprisal value, which is maximized when all the surprisal curves
have the same value and has a minimum of zero if all but a single curve has
probability zero. This is unattainable in the calculation, but can be
arbitrarily close to this state.

```
Entropy_plot(scrfine, SfdList, Qvec, dataList, plotindex=1:n,
plotrange=c(min(scrfine),max(scrfine)), height=1.0, value=0,
ttlsz=NULL, axisttl=NULL, axistxt=NULL)
```

`scrfine` |
A vector of length nfine (usually 101) containing equally spaced points spanning the plotrange. Used for plotting. |

`SfdList` |
A numbered list object produced by a TestGardener analysis of
a test. Its length is equal to the number of items in the test or questions
in the scale. Each member of |

`Qvec` |
The five marker percentile values. |

`dataList` |
A list vector containing objects essential to an analysis. |

`plotindex` |
A set of integers specifying the numbers of the items or questions to be displayed. |

`plotrange` |
A vector of length 2 containing the plot boundaries within or over the score index interval c(0,100). |

`height` |
A positive real number defining the upper limit on the ordinate for the plots. |

`value` |
Number required by ggplot2. Defaults to 0. |

`ttlsz` |
Title font size. |

`axisttl` |
Axis title font size. |

`axistxt` |
Axis text(tick label) font size. |

An entropy curve for each question indexed in the `index`

argument.
A request for a keystroke is made for each question. The answer to question
strongly defines the optimal position of an estimated score index value where
the curve is high value. Values of entropy curves typically range over [0,1].

The plots of the entropy curves specified in `plotindex`

are produced as a side
effect.
If `saveplot`

is TRUE, the plots of item entropy curves specified in
`plotindex`

are bundled into a single postscript or .pdf file and the file name
is defined by `paste(dataList$titlestr,i,'-entropy.pdf',sep="")`

.
The file is then output as a returned value.

Juan Li and James Ramsay

Ramsay, J. O., Li J. and Wiberg, M. (2020) Full information optimal scoring. Journal of Educational and Behavioral Statistics, 45, 297-315.

Ramsay, J. O., Li J. and Wiberg, M. (2020) Better rating scale scores with information-based psychometrics. Psych, 2, 347-360.

`Sensitivity_plot`

,
`Power_plot`

,
`Ffuns_plot`

,
`ICC_plot`

```
# Example 1. Display the item entropy curves for the
# short SweSAT multiple choice test with 24 items and 1000 examinees
# plot the entropy curve for the first item
dataList <- Quant_13B_problem_dataList
SfdList <- Quant_13B_problem_parmList$SfdList
Qvec <- Quant_13B_problem_parmList$Qvec
scrfine <- seq(0,100,len=101)
oldpar <- par(no.readonly=TRUE)
Entropy_plot(scrfine, SfdList, Qvec, dataList, plotindex=1)
par(oldpar)
```

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