I can't understand how to do a survival analysis (?Surv ()) when some
event occurred before the start of observation (left censored). If I
understand correctly, there are two methods. I chose a method with: 1)
time from the start of treatment to the event and 2) the indicator of
the event. I did (in my data) the event indicator so:
1 - event, 2 - event before the start of observation, 0 - no event
---
library(survival)
left_censor_data <- read.table("left.csv", header = TRUE, sep =
";")
#sep = ";" it's right!
dput(left_censor_data, file="left_censor_data") #file attached
left_censor_data
'data.frame': 11 obs. of 2 variables:
$ timee : int 5 151 33 37 75 14 7 9 1 45 ...
$ eventt: int 2 0 0 0 0 0 0 2 0 1 ...
# 1?event, 2 ? event before the start of observation , 0 ? no event
sur <- Surv(time = left_censor_data$timee, event left_censor_data$eventt,
type = "left")
Warning message:
In Surv(time = left_censor_data$timee, event = left_censor_data$eventt, :
Invalid status value, converted to NA
#Why such a message?
#Then everything turns out wrong
On 2020-04-17 20:06, Medic wrote:> I can't understand how to do a survival analysis (?Surv ()) when some > event occurred before the start of observation (left censored). If I > understand correctly, there are two methods. I chose a method with: 1) > time from the start of treatment to the event and 2) the indicator of > the event. I did (in my data) the event indicator so: > 1 - event, 2 - event before the start of observation, 0 - no eventI have no experience of left censoring beyond the text book. Is your left censored data the SAME event or a different event?> --- > library(survival) > left_censor_data <- read.table("left.csv", header = TRUE, sep = ";") > #sep = ";" it's right! > dput(left_censor_data, file="left_censor_data") #file attached > left_censor_data > 'data.frame': 11 obs. of 2 variables: > $ timee : int 5 151 33 37 75 14 7 9 1 45 ... > $ eventt: int 2 0 0 0 0 0 0 2 0 1 ... > # 1?event, 2 ? event before the start of observation , 0 ? no event >So if I read this data correctly the first observation is left censored. What does the time "5" refer to? Is that 5 days BEFORE observation the event happened? Or 5 days after another event happened? My text book understanding of left censored data was that your censored points would have time 0.> sur <- Surv(time = left_censor_data$timee, event > left_censor_data$eventt, type = "left") > Warning message: > In Surv(time = left_censor_data$timee, event = > left_censor_data$eventt, : > Invalid status value, converted to NA > > #Why such a message? > #Then everything turns out wrongIs the censoring type you want LEFT TRUNCATION rather than LEFT. If they are also right censored I think R Surv calls these Counting. See: folk.ntnu.no/bo/TMA4275/Download/R.tutorialDiez.pdf Any help?