S2 X2Calculator

• the cumulative distribution function (cdf, aka lower tail probability), given a χ² value and the number of degrees of freedom (df)
• its complement, the upper tail probability
• the inverse of the cdf (i.e., the χ² value given the cdf and the df )
• the probability density function (pdf)

It also plots the pdf for reference and (hopefully) to facilitate interpretation of values shown.

To use, just edit the desired field, or change the df using the arrows. When doing the latter, you have the option of

• freezing the χ² value to change the cdf and upper tail probability
• freezing the cdf and upper tail probability to change the χ² value

The program is offered with no garanty whatsoever. To the best of my knowledge, it is accurate to the figures given. If you know better, please

It is postcardware (meaning, if you like it, you should send me a nice postcard from your home town, but you should never have to pay for it, or ask anyone to pay you for it), and normaly resides in http://webpages.fc.ul.pt/~pjns/Soft/X2calc/.

It does not require setup, makes no changes to the windows registry, is really simple to install (just unzip the files into a directory of your choice).

If you use the program more than a couple times, please consider Should you use it in work leading to a publication, please cite the program and the above web site.

The program is Copyright Pedro J.N. Silva, 2000. SilvaSquare is a trademark of Pedro J.N. Silva.

download S2 X2Calculator now (zipped)

Have much fun!