[R] Interpretation of t.test results

[Greg Snow]

Omar,

A detailed interpretation of the results are the subject of more than 1 chapter in most introductory statistics books and the topic of several classes/hours of lecture in a standard introductory statistics class.  Your question suggests that you either skipped your intro stats class, or did not learn/do not remember some very fundamental topics that are essential if you are going to be doing any type of inferential statistics.  You should go back an review those chapters of your stats textbook (or get a new/better text and read those chapters) that cover basic hypothesis tests and the t-test in particular.  There are also various online intro classes/videos that may help.  If you then work through an example both by hand and using t.test in R, then you will be able to see which numbers in the example correspond to which parts of the R output as well as gain a better understanding of where the numbers come from and what the proper interpretation is.

This response may seem a bit harsh, but anything else would be doing you a disservice.  Giving you a brief description without the underlying understanding of what is going on would be like having someone else exercise on your behalf, sure you could say that the exercise equipment is being used, but it would have no beneficial effect on your health/weight/waist size.

--
Gregory (Greg) L. Snow Ph.D.
Statistical Data Center
Intermountain Healthcare
greg.snow at imail.org
801.408.8111


> -----Original Message-----
> From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-
> project.org] On Behalf Of Omar Bahy Badreddin
> Sent: Wednesday, October 22, 2008 11:37 PM
> To: r-help at r-project.org
> Subject: [R] Interpretation of t.test results
>
> I have run a t.test in R, and received these results:
>
> Two Sample t-test
>
> data:  rsa and umple
>
> t = 0.9819, df = 10, p-value = 0.3493
>
> alternative hypothesis: true difference in means is not equal to 0
>
> 95 percent confidence interval:
>
>  -76.1541 196.1541
>
> sample estimates:
>
> mean of x mean of y
>
>  508.3333  448.3333
> Can someone give me a detailed interpretation of the above results?
> Specifically, the meaning of the following: t = 0.9819, p-value =
> 0.3493.
>
> Also, how can I utilize the information about the confidence interval
> in
> interpreting my results?
> --
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>
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