[R] Genstat into R - Randomisation test

[Anne Kempel]

Hello everybody,
I have a question. I would like to get a correlation between 
constitutive and induced plant defence which I messured on 30 plant 
species. So I have table with Species, Induced defence (ID), and 
constitutive defence (CD). Since Induced and constitutive defence are 
not independant (so called spurious correlation) I should do a 
randomisation test. I have a syntax of my supervisor in Genstat, but I 
would really like to try this in R.


"data from trade-off.IDCD"
list
variate [nval=1000] slope
calc ID1=ID

graph ID; CD
calc b=corr(ID; CD)
calc slope$[1]=b

"slope$[1] is the correlation before permutating the data"

for i=2...1000
     randomize ID1
     calc b=corr(CD1; ID1)
     calc slope$[i]=b
endfor

hist slope
describe slope
quantile [proportion=!(0.0005,0.005, 0.025, 0.975, 0.995,0.9995)]slope
print slope$[1]
corr[p=corr] ID,CD


DHISTOGRAM [WINDOW=1; ORIENTATION=vertical; KEY=0; BARCOVERING=1.0] 
slope; PEN=2

Does anybody have done something similar and has any idea how to make 
the randomisation part?
I would be very grateful for any help!!
Thanks in advance,
Anne




-- 
Anne Kempel
Institute of Plant Sciences
University of Bern
Altenbergrain 21
CH-3103 Bern
kempel at ips.unibe.ch