Inverse CDF
INVCDF command is useful to help find a value which associates with a specific area given a propotion, especially useful in hypothesis test to find the critical value that would be required to reject the null hypothesis at a particular significant lever. Like the use of CDF command, if no s and m specified, then the distribution is assumed to be standard normal distribution N(0,1).
Here
we use the same example as used in CDF command illustration
( Section 1.3 Exercises 1.62 in BPS page 64). Since we already
found that about 26% soldiers have head circumference greater
than 23.9 inches, we would like to ask, below what value of head
circumference the 84% of soldiers' head circumference will fall?
INVCDF can help us to answer it. Go to Calc--> Probability
Distributions-->Normal and filling in the dialog as shown
right, we get the Z value in Info window.
Info window is shown below.
The answer is 23.8939 inches, which consists with the answer we got before, that 26% soldiers have head circumference greater than 23.9 inches.
Or type command MTB>print k1 to read answer in session window.
