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One-Way ANOVA in Inference App - Printable Version

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One-Way ANOVA in Inference App - mark4flies - 12-19-2016 10:10 PM

I am going through the User Guide to test the latest release and for my own review. I entered some data for four groups like this into the Inference app:

MAKELIST(RANDNORM(50,3),X,1,10) STO> I1 (through I3) and

So I have generated random samples of size 10 from four populations, where the last of them is different by a mean of 3. Then I tested the null hypothesis with the one-way ANOVA. I confirmed this result in the Num view:

F: 3.207 (correct)
P: 0.03446 (correct)

But I was surprised to see this result in the Plot view:
ChiSquare: -10.8849 (?)
P: 0.03446 (correct)

My questions are:
Why is Chi square in the plot view?
Where does the Chi square statistic come form?
Is the graph in the Plot view for a Chi square distribution or the F distribution?


RE: One-Way ANOVA in Inference App - Tim Wessman - 12-20-2016 12:49 AM

I'm guessing it might be plotting when it shouldn't there. I'll take a look at it. I don't think there is a plot view currently for Anova. Thanks!

RE: One-Way ANOVA in Inference App - mark4flies - 12-21-2016 01:55 PM

Well, a plot view with the F PDF and the sample statistic, as done for t tests, might be great for interpretation and instruction of ANOVA.

RE: One-Way ANOVA in Inference App - Tim Wessman - 12-21-2016 02:40 PM

I remember implementing this, so it was strange it wasn't displaying right.

I looked into the source today. Looks like the root culprit was a missing "break" in a switch statement which causes the *label* to display incorrectly as chi2. The graph itself is correct, but the wrong text for the front half/value are being shown. Testers missed this one (and I screwed it up of course Smile ). Thanks!

It should read DF:<num> F:<val> P:<val>.