Hypothesis test for normality on the TI-84?

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Discussion Overview

The discussion revolves around performing a hypothesis test for normality using the TI-84 calculator. Participants explore programming approaches to calculate normal distribution values without relying on visual plots, addressing issues with their code and the accuracy of results.

Discussion Character

  • Technical explanation
  • Mathematical reasoning
  • Debate/contested

Main Points Raised

  • One participant seeks a method to conduct a hypothesis test for normality without visual plots and encounters errors in their programming attempts.
  • Another participant provides a link that may assist with the hypothesis testing process.
  • Multiple participants share code snippets intended to calculate normal cumulative distribution function (CDF) values, noting issues with incorrect outputs, specifically lists filled with zeros.
  • There is a suggestion that the normalcdf function may not accept lists as input for X values, prompting further investigation.
  • One participant updates their code to calculate cumulative frequency and reports that it resolves the issue of zeros but introduces a discrepancy in p-values compared to a statistics textbook.
  • A participant shares a separate macro for calculating cumulative frequency, indicating its successful execution.

Areas of Agreement / Disagreement

Participants express uncertainty regarding the correct placement of the normalcdf function within their code and whether it can handle list inputs. There is no consensus on the accuracy of the p-values obtained from their calculations compared to established references.

Contextual Notes

Participants mention potential issues with their code, including the handling of lists and the accuracy of statistical outputs, but do not resolve these concerns. The discussion reflects ongoing troubleshooting and refinement of programming approaches.

moonman239
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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?
 
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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.

Code:
SortA(L1)
N->dim(L1)
For(I,1,N)
(I/N)->L2(I)
normalcdf(0,L1(I),mean(L1),stdDev(L1))->L3(I)
End
 
moonman239 said:
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.

Code:
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?
 
jedishrfu said:
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 said:
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.

Code:
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:

Code:
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:

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

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