NSM3 (version 1.5)

pSDCFlig: Dwass, Steel, Critchlow, Fligner

Description

Function to compute the P-value for the observed Dwass, Steel, Critchlow, Fligner W statistic.

Usage

pSDCFlig(x,g=NA,method=NA,n.mc=10000)

Arguments

x

Either a list or a vector containing the data.

g

If x is a vector, g is a required vector of group labels. Otherwise, not used.

method

Either "Exact", "Monte Carlo", or "Asymptotic", indicating the desired distribution. When method=NA, "Exact" will be used if the number of permutations is 10,000 or less. Otherwise, "Monte Carlo" will be used.

n.mc

If method="Monte Carlo", the number of Monte Carlo samples used to estimate the distribution. Otherwise, not used.

Value

Returns a list with "NSM3Ch6MCp" class containing the following components:

n

a vector containing the number of observations in each of the k data groups

obs.stat

the observed W statistic for each of the k*(k-1)/2 comparisons

p.val

upper tail P-value corresponding to each W statistic

Details

The data entry is intended to be flexible, so that the groups of data can be entered in either of two ways. For data a=1,2 and b=3,4,5 the following are equivalent:

pSDCFlig(x=list(c(1,2),c(3,4,5))) pSDCFlig(x=c(1,2,3,4,5),g=c(1,1,2,2,2))

Examples

gizzards<-list(site.I=c(46,28,46,37,32,41,42,45,38,44),
              site.II=c(42,60,32,42,45,58,27,51,42,52),
              site.III=c(38,33,26,25,28,28,26,27,27,27),
              site.IV=c(31,30,27,29,30,25,25,24,27,30))
##Takes a little while 
#pSDCFlig(gizzards,method="Monte Carlo")

##Shorter version for demonstration
pSDCFlig(gizzards[1:2],method="Asymptotic")