# Re: [R] creating 3-way tables for mantelhaen.test

From: P Ehlers <ehlers_at_math.ucalgary.ca>
Date: Fri 17 Feb 2006 - 20:50:11 EST

Taka,

Maybe you did something strange when you "replaced Y1's values ....". Is the result a 10-level factor?
The following works for me.

```x1 <- sample(c("y", "n"), 100, replace = TRUE)
x2 <- sample(c("a", "b"), 100, replace = TRUE)
y  <- sample(1:10, 100, replace = TRUE)
y  <- factor(y)

```

dat <- data.frame(x1, x2, y)
dat.xt <- xtabs(~ x1 + x2 + y, data = dat) mantelhaen.test(dat.xt)

Peter Ehlers

Taka Matzmoto wrote:

> Hi R users
> I have serveral binary variables (e.g., X1, X2, X3, X4, X5, X,6, and X7) and
> one continuous variable (e.g., Y1).
>
> I combined these variables using data.frame()
>
> mydata <- data.frame(X1,X2,X3,X4,X5,X6,X7,Y1)
>
> after that, I sorted this data.frame
>
> rank.by.Y1<-order(mydata[,8])
> sorted.mydata<-mydata[rank.by.Y1,]
>
> after that, I replaced Y1's values with values ranging from 1 to 10 ( 1
> represents the lowest group on Y1 and 10 presents the hight group on Y1).
> Now Y1 becomes a grouping variable.
>
> What I like to do is to apply mantelhaen.test for each binary variable pair
> (e.g, X1 and X2, X1 and X3, X1 and X4, .... , X6 and X7)
>
> In order to apply mantelhaen.test, a 3-dimensional contingency table is
> required.
>
> Could you provide some advice on how to create a 3-dimensional contingency
> table (first dimension represents the first variable of variable pair,
> second dimension the second variable of variable pair, and third dimension
> represents 1 to 10 ) and apply mantelhaen.test ?
>
> I looked at arrary, xtabs, table commands but I couldn't figure out yet.
>
> Thank you
>
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