[R] permTREND function in package "perm"

[li li]

Hi all,
  I am trying to figure out how to use the function permTREND correctly in
package "perm". There does not seem to be any examples given for this
function. In the help file, it says the following:

## Default S3 method:
permTREND(x, y, alternative = c("two.sided", "less", "greater"), exact =
NULL, method = NULL, methodRule = methodRuleTREND1,
control=permControl(),...)

## S3 method for class 'formula'
permTREND(formula,data,subset,na.action,...)

where,

x

numeric vector of response scores for the first group
y

numeric vector of either response scores for the second group (for permTS)
or trend scores for each observation (for permTREND)
g

a factor or character vector denoting group membership

But I am still not sure. What does it mean by S3  method for formula?
also, trend score in the explanation for "y" mean what?

Take the data below for example, x should be the count value for the row
corresponding to "Yes", and "y" should be the dose levels "0, 0.15. 0.5,
1.5, 5"?  Need some help on this. Thanks!
    Hanna


> addmargins(dat)

    dose 0 dose 0.15 dose 0.5 dose 1.5 dose 5 Sum

yes      4         3        4        5      8  24

no       4         5        4        3      0  16

Sum      8         8        8        8      8  40

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