st: R: re. information

["Carlo Lazzaro" <carlo.lazzaro@tiscalinet.it>]

Dear Panos:

- the first one-way p-value Pr(T < t) = 0.0000 says that, provided that the
null hypothesis is true (the null hypothesis you test is that population
mean is = 423), repeating a virtually endless number of times the same
experiment using new data each time, with a sample of the same size, the
probability of obtaining a value for the mean < 423 is negligible (0.0000).
Hence the null hypothesis is rejected at 0.05;
- the second one-way p-value Pr(T > t) = 1.0000 is simply the difference
between 1 and the first one-way p-value (ie, 1-0.0000=1). Hence the null
hypothesis is not rejected at 0.05;
- the two-way p-value Pr(|T| > |t|)= 0.0001 says that, provided that the
null hypothesis was true (the null hypothesis you tested is that population
mean is = 423), repeating a virtually endless number of times the same
experiment using new data each time, with a sample of the same size, the
probability of obtaining a value for the mean = 423 is negligible (0.0001).
Hence the null hypothesis is rejected at 0.05.

Hence, the big deal is what you are making hypothesis test for.

Kind regards,
Carlo
-----Messaggio originale-----
Da: owner-statalist@hsphsun2.harvard.edu
[mailto:owner-statalist@hsphsun2.harvard.edu] Per conto di PAPANIKOLAOU P.
Inviato: mercoledì 20 novembre 2013 15:49
A: statalist@hsphsun2.harvard.edu
Oggetto: st: re. information

Dear all,
Running this ttesti, I have got the results below. Does this mean that I
accept the hypothesis that he mean would be 423?
What exactly means each of the three Pr(T?t) seen below, please?

ttesti 12 367 32 423

One-sample t test
------------------------------------------------------------------------
------
         |     Obs        Mean    Std. Err.   Std. Dev.   [95% Conf.
Interval]
---------+--------------------------------------------------------------
------
       x |      12         367    9.237604          32    346.6682
387.3318
------------------------------------------------------------------------
------
    mean = mean(x)                                                t =
-6.0622
Ho: mean = 423                                   degrees of freedom =
11

   Ha: mean < 423               Ha: mean != 423               Ha: mean >
423
 Pr(T < t) = 0.0000         Pr(|T| > |t|) = 0.0001          Pr(T > t) =
1.0000

Thanks, Panos

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