givitiStatCdf: CDF of the Calibration Statistic Under the Null Hypothesis
In givitiR: The GiViTI Calibration Test and Belt

givitiStatCdf returns the cumulative density function of the calibration statistic under the null hypothesis.

1	givitiStatCdf(t, m, devel, thres)

`t`	The argument of the CDF. Must be a scalar value.
`m`	The scalar integer representing the degree of the polynomial at the end of the forward selection.
`devel`	A character string specifying if the model has been fit on the same dataset under evaluation (`internal`) or if the model has been developed on an external sample (`external`).
`thres`	A numeric scalar between 0 and 1 representing the significance level adopted in the forward selection.

A number representing the value of the CDF evaluated in t.

givitiCalibrationBelt and plot.givitiCalibrationBelt to compute and plot the calibaration belt, and givitiCalibrationTest to perform the associated calibration test.