My aplogies:
The Table of effects did not come through as I had intended them to. HEre they
are reformatted:
Again I would like to see someone actually run mahalanobis() for this data set
to arrive at ?1 and ?2. I do not know what exactly (after reading the manual)
goes in for x,center,or cov. Seeing an actual [R] printout of it being done
(from start to finish) would go a long way towards my learning.
Effect Sizes
Contrasts| Dependent Variables
Friends Parents Strangers All
Young-Middle -1.8768797* -3.2842941* -1.1094004* ?1
Middle-Old 1.34900725* 1.54919532* -2.0107882* ?2
Gender Age, Friend.Agression, Parent.Agression, Stranger.Agression
1 f y 8 7 8
2 f y 5 6 8
3 f y 6 3 7
4 f y 5 5 7
5 f m 15 13 10
6 f m 13 11 9
7 f m 12 12 9
8 f m 18 10 7
9 f o 11 11 10
10 f o 10 4 12
11 f o 12 9 12
12 f o 9 8 14
13 m y 13 7 7
14 m y 9 5 10
15 m y 11 4 4
16 m y 15 3 4
17 m m 14 12 8
18 m m 10 15 11
19 m m 12 11 8
20 m m 10 9 9
21 m o 10 8 11
22 m o 13 11 13
23 m o 9 8 12
24 m o 7 9 16
> From: tyler_rin...@hotmail.com
> To: r-help@r-project.org
> Date: Sun, 20 Mar 2011 01:53:47 -0400
> Subject: [R] Using the Mahalanobis Function
>
>
>
>
>
> Hello all,
>
> I am a 2 month newbie to R and am stumped. I have a data set that I've run
> multivariate stats on using the manova function (I included the data set).
> Now it comes time for a table of effect sizes with significance. The
> univariate tests are easy. Where I run into trouble filling in the table of
> effect sizes is the Mahalanobis D as an effect size. I've included the table
> so you can see what group's I'm comparing. I know there's a great function
> for filling in ?1 and ?2 : mahalanobis(x, center, cov, inverted=FALSE, ...)
>
> The problem is I lack the knowledge around cluster analysis of what goes into
> the function for [x, center, & cov.] I have only a basic understanding of
> this topic (a picture of a measured distance between two clusters on a
> graph). Could someone please use my data set or a similar one (a multivariate
> with at least 3 outcome variables) and actually run this function
> (mahalanobis). Then please send me your output from [R] starting from the
> data set all the way to the statistic. PS I know the Mahalanobis D should be
> ?1=3.93 & ?2=3.04.
>
> The Y,M,O in the data set stands for young, middle, old.
>
> I am running the latest version of R on a windows 7 machine.
>
>
>
>
>
>
> Effect Sizes
>
>
>
> Contrasts
>
> Dependent Variables
>
>
>
>
>
>
> Friends
>
> Parents
>
> Strangers
>
> All
>
>
> Young-Middle
>
> -1.8768797*
>
> -3.2842941*
>
> -1.1094004*
>
> ?1
>
>
> Middle-Old
>
> 1.34900725*
>
> 1.54919532*
>
> -2.0107882*
>
> ?2
>
> Gender Age Friend.Agression Parent.Agression Stranger.Agression
> 1 f y 8 7 8
> 2 f y 5 6 8
> 3 f y 6 3 7
> 4 f y 5 5 7
> 5 f m 15 13 10
> 6 f m 13 11 9
> 7 f m 12 12 9
> 8 f m 18 10 7
> 9 f o 11 11 10
> 10 f o 10 4 12
> 11 f o 12 9 12
> 12 f o 9 8 14
> 13 m y 13 7 7
> 14 m y 9 5 10
> 15 m y 11 4 4
> 16 m y 15 3 4
> 17 m m 14 12 8
> 18 m m 10 15 11
> 19 m m 12 11 8
> 20 m m 10 9 9
> 21 m o 10 8 11
> 22 m o 13 11 13
> 23 m o 9 8 12
> 24 m o 7 9 16
>
> [[alternative HTML version deleted]]
>
> ______________________________________________
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> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
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