[R] a new-bie question about obtaining certain value from the printout

[Greg Snow]

You need to save the output in order to do something with it (the
default if you don't save the output is to call the print method, so
what you are seeing is the results of calling print.htest on the return
value from t.test).

Save the output by doing something like:

> out <- t.test(c(1:5,7:11), y=c(1:10), 
+ alternative = c("two.sided"), paired = TRUE)

Now the results are stored in "out" (or whatever better name you come up
with)

To access the p-value you can do:

> out$p.value

Or use that in another expression.

The details on what comes after the '$' can be found in this case from
the t.test help page, or in general using the str function:

> str(out)

Gives a wealth of information (sometimes too much) on the components of
the returned object.

Hope this helps,

-- 
Gregory (Greg) L. Snow Ph.D.
Statistical Data Center
Intermountain Healthcare
greg.snow at intermountainmail.org
(801) 408-8111
 
 

> -----Original Message-----
> From: r-help-bounces at stat.math.ethz.ch 
> [mailto:r-help-bounces at stat.math.ethz.ch] On Behalf Of kurt Zhao
> Sent: Wednesday, August 29, 2007 2:53 PM
> To: r-help at stat.math.ethz.ch
> Subject: [R] a new-bie question about obtaining certain value 
> from the printout
> 
> Hi everyone,
> 
> I am quite new to R.
> 
> my command is
> t.test(c(1:5,7:11), y=c(1:10),alternative = c("two.sided"), 
> paired = TRUE)
> 
> The output is
> 
>         Paired t-test
> 
> data:  c(1:5, 7:11) and c(1:10)
> t = 3, df = 9, p-value = 0.01496
> alternative hypothesis: true difference in means is not equal to 0
> 95 percent confidence interval:
>  0.1229738 0.8770262
> sample estimates:
> mean of the differences
>                     0.5
> According to the reference:
> 
> Value
> A list with class "htest" containing the following components:
> p.value the p-value for the test.
> 
> How can I get only the p.value as the output instead of the 
> whole print out?
> 
> Thanks a lot!
> 
> -Kurt
> 
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