Normal Distribution Programs
NORM (for the TI-83/TI-83-Plus)
If you have a TI-83, and fear you may forget how to use the built in
normal distribution functions, the program NORM organizes them so you can
either look at the probability of a z-score, or a z-score for a probability
INVNORM82 (for the TI-82)
For calculators without the built-in distribution functions, the
fnInt can be used effectively. invnorm will find a z-score based on a
probability.
NORMCDF82 (for the TI-82)
For calculators without the built-in distribution functions, the
fnInt can be used effectively. NORMCDF82 will compute a probability
for upper and lower tails, or a range. Note you can sacrifice speed
for accuracy (and vice versa) by manipulating the tolerance from
1E-3 to 1E-6.
Download normti.zip if you have a TI- graph link
Other Ideas
You can also produce your own table (which will take about 10 minutes to
make), and then write a simple lookup program that uses it. For instance,
If you produce the table from -3.00 to +3.00, stepping in .01 increments:
Then the cumulative probability for -1.64 would be in lGAUSS( 301+ (-1.64)*100 )
That is (301+x*100). You can easily write another program to find the invNorm value
as well. When you found the correct amount in the list's contents the index (location in the
list) can be converted to a z-score by dividing by 100 and subtracting 301 z = (-301 + i)/100)
(so the 70th entry (=.01044) would correspond with z=(-301+70)/100=-2.31 )
Other Calc Programs and Data