|Developer(s)||Institute for Land Reclamation and Improvement (ILRI)|
|Operating system||Microsoft Windows|
In statistics and data analysis the application software NormDis is a free and user-friendly calculator for the determination of the cumulative probability Pc(Xr) for any random variable (X) following the normal distribution. Here, the cumulative probability Pc(Xr) stands for the probability P that X is less than a reference value Xr of X. Biefly : Pc(Xr) = P(X<Xr).
The probability (Pi) that X occurs in an interval between an upper limit (U) and a lower limit (L) can be found from:
- Pi = P(L<X<U) = Pc(U) - Pc(L) .
Thus, using the calculator twice, namely for Xr=U and Xr=L, and subtracting the results, one finds the value of Pi that L<X<U.
- b0 = 0.2316419, b1 = 0.319381530, b2 = −0.356563782, b3 = 1.781477937, b4 = −1.821255978, b5 = 1.330274429.
Here, is the standard normal probability density function (PDF):
The NormDis program provides graphics for the various values computed with the calculator. See the examples to left and right.