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View Full Version : Hypothesis test for normality on the TI-84?


moonman239
Jan9-12, 05:23 PM
I'm trying to run a hypothesis test to see if a data set follows a normal distribution. I don't want to look at a plot. Is there any way? I tried to build a program that uses the built-in normal distribution functions to calculate how far the points on a normality plot would fall from forming a straight line, but I get errors.

Any ideas?

jedishrfu
Jan9-12, 05:26 PM
CHeck this out it may help:

http://mathforum.org/library/drmath/view/72065.html

moonman239
Jan9-12, 06:01 PM
Here is the code I am using. Instead of filling List 3 with the normal CDF values, it fills List 3 with a bunch of 0's.


SortA(L1)
N->dim(L1)
For(I,1,N)
(I/N)->L2(I)
normalcdf(0,L1(I),mean(L1),stdDev(L1))->L3(I)
End

jedishrfu
Jan9-12, 07:37 PM
Here is the code I am using. Instead of filling List 3 with the normal CDF values, it fills List 3 with a bunch of 0's.


SortA(L1)
N->dim(L1)
For(I,1,N)
(I/N)->L2(I)
normalcdf(0,L1(I),mean(L1),stdDev(L1))->L3(I)
End

Shouldnt the normalcdf be outside loop?

moonman239
Jan10-12, 10:19 AM
Shouldnt the normalcdf be outside loop?
I don't think normalcdf will take lists for X values. But I will try that as soon as I can.
As it happens, I created another macro that just calculates the cumulative frequency. That one does work. I know how to have my normalcdf macro execute my cumulative frequency macro. For the reference, I just press "PRGM," in the EXEC highlight that macro and press "ENTER," that big button on the bottom-right.

moonman239
Jan13-12, 05:53 PM
Here is the code I am using. Instead of filling List 3 with the normal CDF values, it fills List 3 with a bunch of 0's.


SortA(L1)
N->dim(L1)
For(I,1,N)
(I/N)->L2(I)
normalcdf(0,L1(I),mean(L1),stdDev(L1))->L3(I)
End

Update: I changed the code.

Now it's this:

prgmCUMFREQ
(L1-mean(L1))/stdDev(L1)->L3
For (I,1,dim(L1))
normalcdf(-1e99,L3(I),0,1)->L4(I)
End


Now it won't give me those zeroes.

But now I have another problem. When I fill in data from my statistics textbook, I get a different p-value than what my statistics textbook reads. I am reasonably certain I did not mistype any data.

UPDATE: Here's the code for my cumulative frequency macro:

PROGRAM:CUMFREQ
SortA(L1)
For(I,1,dim(L1))
I/dim(L1)->L2(I)
End