help with nomogram function

Frank Harrell wrote
 

On Wed, 05 Nov 2003 09:22:34 +1000
Ross Darnell <r.darnell at uq.edu.au> wrote:

I have fitted a logistic regression model

failed.lr2$call

lrm(formula = failed ~ Age + task2 + Age:task2, data = time.long, 
    na.action = na.omit)

Use Age*task2 and omit na.action as na.omit is the default

using the Design package functions and would like to generate a
nomogram from this model.

the datadist information is generated and stored in

ddist

                time.long$Age time.long$task2
Low:effect                 45            <NA>
Adjust to                  56       both.foam
High:effect                68            <NA>
Low:prediction             21       both.foam
High:prediction            80           right
Low                        20       both.foam
High                       80           right

This looks most strange.  You did not include the original code but I
suspect you had $ in a term.  $ should not appear in column headings
above.  Design wants you to use data= or attach, and avoid $ in terms.

Values:

time.long$task2 : both.foam left right 

The model fitted and then when I try the nomgram function

nomogram(failed.lr2)

Error in value.chk(at, i, NA, -nint, Limval, type.range = "full") : 
	variable Age does not have limits defined by datadist

I get an error. The NA values in ddist seem to be the problem but I
don't understand the datadist information.

I tried using the data argument in datadist

names(my.data)

[1] "subject" "Age"     "failed"  "task"   

ddist <- datadist(Age,task,data=my.data)

Error in datadist(Age, task, data = my.data) : 
	Object "Age" not found

Strange.

Thanks
Ross Darnell


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