ecology-bounces@r-
>> project.org] on behalf of Richard Boyce [boy...@nku.edu]
>> Sent: 24 March 2014 13:23
>> To: r-sig-ecology@r-project.org
>> Subject: Re: [R-sig-eco] report out by t.test
>>
>> Mike,
>>
>> There is no way that your data meet the assu
behalf of Richard Boyce [boy...@nku.edu]
Sent: 24 March 2014 13:23
To: r-sig-ecology@r-project.org
Subject: Re: [R-sig-eco] report out by t.test
Mike,
There is no way that your data meet the assumptions of a t-test (normal
distributions, equal variance). A nonparametric Mann-Whitney (aka Wilcoxon
nen
From:
r-sig-ecology-boun...@r-project.org<mailto:r-sig-ecology-boun...@r-project.org>
[r-sig-ecology-boun...@r-project.org<mailto:r-sig-ecology-boun...@r-project.org>]
on behalf of Richard Boyce [boy...@nku.edu<mailto:boy...@nku.edu>]
S
g] On Behalf Of Jari Oksanen
Sent: Monday, 24 March 2014 10:43 PM
To: Richard Boyce; r-sig-ecology@r-project.org
Subject: Re: [R-sig-eco] report out by t.test
Except that t-test does not assume that *observations* are normally
distributed, nor that variances are equal.
Avoid non-parametric tests:
From: r-sig-ecology-boun...@r-project.org [r-sig-ecology-boun...@r-project.org]
on behalf of Richard Boyce [boy...@nku.edu]
Sent: 24 March 2014 13:23
To: r-sig-ecology@r-project.org
Subject: Re: [R-sig-eco] report out by t.test
Mike,
There is no way that your data meet the assumptions of a t-test
Mike,
There is no way that your data meet the assumptions of a t-test (normal
distributions, equal variance). A nonparametric Mann-Whitney (aka Wilcoxon)
test is much better suited to your data.
Here's what I got when I ran it:
Q<-c(13,0,10,2,0,0,1,0,0,1,5)
WD<-c(0,0,1,0,0,0,0,0,0,0,1)
wilcox.
I'd like to add that to me Q and WD don't look normally distributed.
Isn't that a prerequisite for using the t.test to test for diffrences
between the means? Please correct me if I am wrong.
Cheers,
Mango
-
B.-Markus Clarin aka Mango
--
The sentence "alternative hypothesis: true difference in means is not equal to
0" is stating what the alternative hypothesis is and not that your particular
difference in means is significantly different from zero. That sentence would
appear (when you have a two-tailed test) no matter what the
