[R] cox model

[post .]

I need a R-code for a situation that is well described in the sas help. I
would be very grateful for the help!
"Time-dependent variables can be used to model the effects of subjects
transferring from one treatment group to another. One example of the need
for such strategies is the Stanford heart transplant program. Patients are
accepted if physicians judge them suitable for heart transplant. Then, when
a donor becomes available, physicians choose transplant recipients
according to various medical criteria. A patient’s status can be changed
during the study from waiting for a transplant to being a transplant
recipient. Transplant status can be defined by the time-dependent covariate
function z=z(t) as:
z(t)= 0 (if the patient has not received the transplant at time t)
and 1 (if has received)



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[R] cox model

[post .]

I need a R-code for a situation that is well described in the sas help. I
would be very grateful for the help!
"Time-dependent variables can be used to model the effects of subjects
transferring from one treatment group to another. One example of the need
for such strategies is the Stanford heart transplant program. Patients are
accepted if physicians judge them suitable for heart transplant. Then, when
a donor becomes available, physicians choose transplant recipients
according to various medical criteria. A patient’s status can be changed
during the study from waiting for a transplant to being a transplant
recipient. Transplant status can be defined by the time-dependent covariate
function z=z(t) as:
z(t)= 0 (if the patient has not received the transplant at time t)
and 1 (if has received)


Без
вирусов. www.avast.ru

<#DAB4FAD8-2DD7-40BB-A1B8-4E2AA1F9FDF2>

[[alternative HTML version deleted]]

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and provide commented, minimal, self-contained, reproducible code.

[R] factor conversion to date/time

[marjolein post]

Hi, I've been trying to convert numbers from an online temperature database
into dates and time that R recognizes. I've tried as.Date, as.POSIXlt and 
strptime  the problem is that the database has put a T between the numbers and 
R will not accept any conversions. currently it sees the date as a factor with 
the format  as 1981-01-02T08:00I would like to keep only the year and month, 
but my primary focus is to get R to recognize it as a date.

Thank you for your help. cheers,Marjolein   
  
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[R] NAs introduced by coercion warning?

[Omar Gonzalez Post]

I'm running cluster analysis on a data frame but when I calculate the distance 
I get this warning "NAs introduced by coercion".  What does this mean?

  
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[R] distance matrices

[Omar Gonzalez Post]

i'm working on some distance matrices and i was wondering if there is a way to 
export the matrices from R to excel.
OG
thanks
  
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[R] some QCA questions

[Suzanne van der Post]

Dear Adrian Dusa, others,
 
I've recently started to learn R in order to use the QCA package because
i think it might offer what other QCA packages don't: possibilities for
quite a few conditions and large n. However, can someone tell me approx.
how much RAM i need to run QCA on set of  +/- 400.000 cases and +/- 15
conditions? (or differently: how much time will it take with RAM of a
certain size?)
Also I'm very keen on hearing any news on the fuzzy and multivalue
options for R...How's that comming along?
 
Thanks a lot for any information you can provide!
And of course major thanks for all the information you've already
provided for me in existing manuals, R-fora etc. Great work!
 
Greetings, 
Suzan van der Post
 
 
 



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