[R] Plotting Coxph model with an interaction.

[Gerrit Eichner]

Hi, John,

it should work the same way as without interaction (but make sure
to use the fitted object "coxfit", not just "fit" in our call of
survfit, and note that age*rx already expands to age + rx + age:rx
so that age + rx is redundant in your formula):

coxfit <- coxph(Surv(futime, fustat) ~ age+rx+age*rx, data = ovarian)
plot(survfit(coxfit, newdata=data.frame(age=60,rx=2)))

Or do I missunderstand your question?

  Hth  --  Gerrit

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Am 20.05.2021 um 21:15 schrieb Bert Gunter:
> Perhaps this might be useful:
> 
> https://rpubs.com/tf_peterson/interactionplotDemo
> 
> Bert Gunter
> 
> "The trouble with having an open mind is that people keep coming along and
> sticking things into it."
> -- Opus (aka Berkeley Breathed in his "Bloom County" comic strip )
> 
> 
> On Thu, May 20, 2021 at 10:29 AM Sorkin, John <jsorkin using som.umaryland.edu>
> wrote:
> 
>> Colleagues,
>>
>> I hope someone can tell me how to plot a cox model that contains an
>> interaction term.
>>
>> I know that plot(survfit(. . . . )) can be used to plot a Cox model, i.e..
>> coxfit <- coxph(Surv(futime, fustat) ~ age+rx, data = ovarian)
>> plot(survfit(fit, newdata=data.frame(age=60,rx=2)))
>>
>> but I don't know how to plot a cox model with an interaction, i.e.
>>
>> coxfit <- coxph(Surv(futime, fustat) ~ age+rx+age*rx, data = ovarian)
>> plot(survfit(fit, newdata=data.frame(???????)))
>>
>> Thank you,
>> John
>>
>> John David Sorkin M.D., Ph.D.
>> Professor of Medicine
>> Chief, Biostatistics and Informatics
>> University of Maryland School of Medicine Division of Gerontology and
>> Geriatric Medicine
>> Baltimore VA Medical Center
>> 10 North Greene Street
>> GRECC (BT/18/GR)
>> Baltimore, MD 21201-1524
>> (Phone) 410-605-7119
>> (Fax) 410-605-7913 (Please call phone number above prior to faxing)
>>
>>
>> ______________________________________________
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>>
> 
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> 
> ______________________________________________
> R-help using r-project.org mailing list -- To UNSUBSCRIBE and more, see
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>