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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Dear Omar
Your t.test is telling that the 2 groups are not different. Now it is not clear
if you want to compute the CI for the difference or for each group. If the
former, then the outputs provides you with that information.
It?d be clearer if you provide the full syntax of your t.test. For example,
let?s suppose I have 2 groups as vectors ?a? and ?b?, they are independent, they
have similar homogeneity, I want to use a two-tailed test, and I want a 95%CI
for the difference, so I type
t.test(a, b, alternative = c("two.sided"), paired = FALSE, var.equal =
TRUE,
conf.level = 0.95)
Cheers,
Fer
You may find these links helpful for the introduction to the t-test and the interpretation of the t-test results: http://www.tufts.edu/~gdallal/LHSP.HTM See: Student's t Test for Independent Samples http://www.itl.nist.gov/div898/handbook/eda/section3/eda353.htm Timur -- Timur Shtatland, Ph.D. Senior Bioinformatics Scientist Agencourt Bioscience Corporation - A Beckman Coulter Company 500 Cummings Center, Suite 2450 Beverly, MA 01915 office: 978-867-2641, fax: 978-867-2920 email: timur [dot] shtatland [at] rem0veth1s agencourt [dot] com http://www.agencourt.com/ On Thu, Oct 23, 2008 at 1:36 AM, Omar Bahy Badreddin <oobahy@gmail.com>wrote:> 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? > -- > . > > [[alternative HTML version deleted]] > > ______________________________________________ > R-help@r-project.org mailing list > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide > http://www.R-project.org/posting-guide.html > and provide commented, minimal, self-contained, reproducible code. >[[alternative HTML version deleted]]
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? > -- > . > > [[alternative HTML version deleted]] > > ______________________________________________ > R-help at r-project.org mailing list > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide http://www.R-project.org/posting- > guide.html > and provide commented, minimal, self-contained, reproducible code.