So basically im using data from the survival package which is:
require(survival) library(KMsurv) data("pneumon") attach(pneumon)
And I need to use specific variables as required. This is done in the next step:
chldage1<-ifelse(chldage<12,1, ifelse(chldage>=12,0,3)) pneumon$nsibs[pneumon$nsibs>3]<-3 nsibs[is.na(nsibs)]<-0 wmonth[wmonth>=4 & wmonth<=6]<-4 wmonth[wmonth>=7]<-5
Now I'm required to perform a log-rank test to o determine whether there is a statistically significant difference in the hazard rates of pneumonia given different numbers of siblings. If there is, perform multiple comparisons to decide which groups differ at the overall 5% significance level. Use Bonferroni correction.
So here I use the coding for the log-rank test:
> survdiff(Surv(wmonth,chldage1)~nsibs,data=pneumon) Call: survdiff(formula = Surv(wmonth, chldage1) ~ nsibs, data = pneumon) N Observed Expected (O-E)^2/E (O-E)^2/V nsibs=0 1801 510 600.9 13.74 34.42 nsibs=1 1156 410 369.1 4.54 7.88 nsibs=2 383 153 117.2 10.92 14.25 nsibs=3 130 51 36.9 5.41 6.58 Chisq= 40.5 on 3 degrees of freedom, p= 8.51e-09
Finally my question is, how do I interpret these results in order to determine if there is a statistical significance according to my chi-square and p-value?