[R-sig-eco] What statistical analysis should I take??

[Dunbar, Michael J.]

Dear Yong

The simplest approach would be to calculate a phi value for each stream, and then apply conventional anova.

There is some background on phi here:
http://en.wikipedia.org/wiki/Particle_size_%28grain_size%29

There is an example of a simple algorithm to calculate phi from discrete categories here (Appendix E), this may need modifying slightly for your categories:
http://www.wfduk.org/bio_assessment/bio_assessment/rivers_invertebrates

regards
Mike


-----Original Message-----
From: r-sig-ecology-bounces at r-project.org [mailto:r-sig-ecology-bounces at r-project.org] On Behalf Of Yong Zhang
Sent: 12 January 2011 05:42
To: r-sig-ecology
Subject: [R-sig-eco] What statistical analysis should I take??

Hello all,

Now, I have a big trouble, thing is like that I sampled the sediment of 10 streams. These streams can be divided into two groups, group A and B , each group contains 5 streams. 

The sediment also can be divided into 4 types (according to the diameter of the sediment particle :sand < 2mm, gravel  2--64mm, cobble  64---256mm and boulder  >256mm), I measured 100 sediment particles per stream, and the number of each kind sediment particle has been recorded. 

My sediment datas are something like:
group
A:               sand     gravel   cobble  boulder
1                 10         20          20        50
2                 20          30          20         30
3                 ........etc....
4
5

B:              sand          gravel    cobble  boulder
1                0              5             80         15
2                10             20             15       55
3                ...........etc............
4 
5          

I aim to explore whether the sediment composition is significantly different between the two groups, or not. Could anyone tell me what analysi should I take, and any of your hint or suggestion will be greatly appreciated. 

All the best,

Yong


ps: If anyone have any idea, please tell me in details, because I am green. Thanks very much for your time!

2011-01-12 


Yong Zhang, Ph.D. 
Lab of aquatic insects & stream ecology
Dept.of Entonology, Nanjing Agricultural University Nanjing, 210095,China Phone number:  (+86) -25-84395241 E-mail:2010202035 at njau.edu.cn
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