Description Usage Arguments Details Value Note Author(s) Examples

Estimates the probability of observing each rating category given a set of ordered rating category thresholds.

1 | ```
msdprob(x, thresholds)
``` |

`x` |
a real number or a vector of real numbers with no NA representing a set of person minus item measures. |

`thresholds` |
a numeric vector of ordered rating category thresholds with no NA. |

It is assumed that `thresholds`

partitions the real line into `length(thresholds)+1`

ordered intervals that represent the rating categories.

A matrix of probabilities where each of the `length(thresholds)+1`

rows represents a different rating category (lowest rating category is the top row) and each of the `length(x)`

columns represents a different person minus item measure.

`msdprob`

can be used to create probability curves, which represent
the probability of rating an item with each rating category as a function
of the person measure minus item measure (see Examples).

Chris Bradley (cbradley05@gmail.com)

1 2 3 4 5 6 7 8 9 10 11 12 13 | ```
# Simple example
p <- msdprob(c(1.4, -2.2), thresholds = c(-1.1, -0.3, 0.5, 1.7, 2.2))
# Plot probability curves — each curve represents the probability of
# rating an item with a given rating category as a function of the
# person measure minus item measure.
x <- seq(-6, 6, 0.1)
p <- msdprob(x, thresholds = c(-3.2, -1.4, 0.5, 1.7, 3.5))
plot(0, 0, xlim = c(-6, 6), ylim = c(0, 1), type = "n",
xlab = "Person minus item measure", ylab = "Probability")
for (i in seq(1, dim(p)[1])){
lines(x, p[i,], type = "l", lwd = "2" , col = rainbow(6)[i])
}
``` |

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