How do you find the value of Q function?
Q(x) = 1 – CDF = P(X > x)
The y-axis represents probabilities from 0 to 1. The x-axis represents standard deviations, or z-scores. Calculating the function by hand is relatively simple: find the CDF, and subtract from one. Some software programs find the Q function directly.
How do you find the inverse of a Q function?
z = qfuncinv( y ) returns the input argument of the Q function for which the output value of the Q function is y .