- #1

- 195

- 0

## Main Question or Discussion Point

How do you use a TI-89 to get phi(z) when you do a confidence interval, i.e.

phi(z) = 1/2 (1 + erf(z / sqrt(2)))

The Normal CDF function has lower and upper values so I don't see how I can do it, and erf(z) doesn't do anything when I enter it so it must not be built in. Integrating the error function doesn't work either, I think because it's nonstandard.

ex - using TI 89 to calculate phi(4.5) = .999997

phi(z) = 1/2 (1 + erf(z / sqrt(2)))

The Normal CDF function has lower and upper values so I don't see how I can do it, and erf(z) doesn't do anything when I enter it so it must not be built in. Integrating the error function doesn't work either, I think because it's nonstandard.

ex - using TI 89 to calculate phi(4.5) = .999997