Re: p-value issue


Richard Ulrich wrote:
On 10 Dec 2006 12:55:43 -0800, "Ethan.Johnsons@xxxxxxxxx"
<Ethan.Johnsons@xxxxxxxxx> wrote:

I have these two data sets and plotted them one by one, compare, and
confirm that both return the same curve and shape, close to identical.


x=(3.05176E-05,0.000457764,0.003204346,0.0138855,0.04165649,0.09164429,
0.1527405,0.1963806,0.1963806,0.1527405,0.09164429,0.04165649,0.0138855,
0.003204346,0.000457764,3.05176E-05)
y=(0.0000306,0.0004566,0.0031985,0.0139083,0.0415539,0.0917678,
0.1528134,0.1962831,0.1962994,0.1527996,0.0917336,0.0415497,
0.0139308,0.0031917,0.0004529,0.0000301)

This makes me think that the p-value must be very significant (less
0.05), but if I run Chi-Square, I get p-value = 0.3021.

Should I use a different test to see if they are "identical" or
not?

This post shows a lot of confusion --

1) Which "chi-square" test? The contingency table test is applied
to *counts*, preferably counts greater than 5.0; and all of
your numbers are less than 1. Whatever test you use, there will
need to be some reference to sample size, either in computing
the test or in looking up a p-level.

2) If a Goodness of Fit test has a big chi-square, that says that
the distributions are *different*. So, assuming that you have
used some test that is appropriate, your result says what you
hoped -- your sample size is not large enough to make their
difference 'statistically significant.'

--
Rich Ulrich, wpilib@xxxxxxxx
http://www.pitt.edu/~wpilib/index.html

I used Pearson's Chi-squared test.
I also used t-test, etc, but the p-value is very high. With these data
sets, I want to compare the similarity, which it is very close to
identical if you plot them. I thought that sample size 9 would be
enough to compare two data sets. That is why I was wondering if there
is another test to confirm the similarity.

thx

ej

.

Relevant Pages

  • Re: p-value issue
    ... Richard Ulrich wrote: ... This makes me think that the p-value must be very significant (less ... 0.05), but if I run Chi-Square, I get p-value = 0.3021. ... is another test to confirm the similarity. ...
    (sci.stat.math)
  • Re: p-value issue
    ... This makes me think that the p-value must be very significant (less ... 0.05), but if I run Chi-Square, I get p-value = 0.3021. ... Rich Ulrich, wpilib@xxxxxxxx ... is another test to confirm the similarity. ...
    (sci.stat.math)
  • Re: p-value issue
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  • Re: p-value issue
    ... confirm that both return the same curve and shape, ... This makes me think that the p-value must be very significant (less ... 0.05), but if I run Chi-Square, I get p-value = 0.3021. ... the distributions are *different*. ...
    (sci.stat.math)
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