R help - Jun 2005 - how to rectify t.test( ) error

Hi All,
 
 I get the following error when i perform a t.test.
 
studentt<-apply(tlr, 1, function(x) t.test(x[2:6],
x[7:11],var.equal=TRUE)$p.value)
 
# tlr is a table of 11 columns and 22500 rows. I am not able to post tlr due to
its size.

Error in if (stderr < 10 * .Machine$double.eps * max(abs(mx), abs(my)))
stop("data are essentially constant") :
        missing value where TRUE/FALSE needed
In addition: Warning messages: 
1: argument is not numeric or logical: returning NA in: mean.default(x) 
2: argument is not numeric or logical: returning NA in: mean.default(y) 
 
Could someone kindly give me pointers regarding the error. This worked fine with
2 other data sets.

Thank You.
 
Choudary Jagarlamudi
Instructor
Southwestern Oklahoma State University
STF 254
100 campus Drive
Weatherford OK 73096
Tel 580-774-7136

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"Jagarlamudi, Choudary" <choudary.jagar at swosu.edu> writes:
> Hi All,
>  
>  I get the following error when i perform a t.test.
>  
> studentt<-apply(tlr, 1, function(x) t.test(x[2:6],
x[7:11],var.equal=TRUE)$p.value)
>  
> # tlr is a table of 11 columns and 22500 rows. I am not able to post tlr
due to its size.
> 
> Error in if (stderr < 10 * .Machine$double.eps * max(abs(mx), abs(my)))
stop("data are essentially constant") :
>         missing value where TRUE/FALSE needed
> In addition: Warning messages: 
> 1: argument is not numeric or logical: returning NA in: mean.default(x) 
> 2: argument is not numeric or logical: returning NA in: mean.default(y) 
>  
> Could someone kindly give me pointers regarding the error. This worked fine
with 2 other data sets.
I would conjecture that your table is nonnumeric. What is mode(tlr)?
(-- or mode(as.matrix(tlr)) if tlr is a data frame).

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