The following applet allows the user to calculate the probability, alpha, of a Chi-Square random variable with n degrees of freedom and a cut-off of x.
Or, it will allow the user to calculate the cut-off, x, of a Chi-Square random variable given its degrees of freedom, n, and its probability, alpha.
The algorithms used to calculate the probability and cut-off in this applet were borrowed from John C. Pezzullo, Adjunct Instructor, Department of Biomathematics and Biostatistics, Georgetown University Medical Center.