Hello,

Vous ĂȘtes française?
It shows, in english it would be 'exponential', with an 'a'.

Worked with me, after reading the manual.


dataexp <- read.table(text="
vi      Ti
1  26    5.79
2  26 1579.52
3  26 2323.70
4  28   68.85
[...]
73 38    0.39
74 38    1.13
75 38    0.09
76 38    2.38
", header=TRUE)

#  Better in a post to R-Help is the output of dput()
# It looks like the following line, without the assignment.
 dput(dataexp)
dataexp <-
structure(list(vi = c(26L, 26L, 26L, 28L, 28L, 28L, 28L, 28L,
30L, 30L, 30L, 30L, 30L, 30L, 30L, 30L, 30L, 30L, 30L, 32L, 32L,
32L, 32L, 32L, 32L, 32L, 32L, 32L, 32L, 32L, 32L, 32L, 32L, 32L,
34L, 34L, 34L, 34L, 34L, 34L, 34L, 34L, 34L, 34L, 34L, 34L, 34L,
34L, 34L, 34L, 34L, 34L, 34L, 36L, 36L, 36L, 36L, 36L, 36L, 36L,
36L, 36L, 36L, 36L, 36L, 36L, 36L, 36L, 38L, 38L, 38L, 38L, 38L,
38L, 38L, 38L), Ti = c(5.79, 1579.52, 2323.7, 68.85, 426.07,
110.29, 108.29, 1067.6, 17.05, 22.66, 21.02, 175.88, 139.07,
144.12, 20.46, 43.4, 194.9, 47.3, 7.74, 0.4, 82.85, 9.88, 89.29,
215.1, 1.75, 0.79, 15.93, 3.91, 0.27, 0.69, 100.58, 27.8, 13.95,
53.24, 0.96, 4.15, 0.19, 0.78, 8.01, 31.75, 7.35, 6.5, 8.27,
33.91, 32.52, 3.16, 4.85, 2.78, 4.67, 1.31, 12.06, 36.71, 72.89,
1.97, 0.59, 2.58, 1.69, 2.71, 25.5, 0.35, 0.99, 3.99, 3.67, 2.07,
0.96, 5.35, 2.9, 13.77, 0.47, 0.73, 1.4, 0.74, 0.39, 1.13, 0.09,
2.38), status = c(1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1)), .Names = c("vi",
"Ti", "status"), row.names = c("1", "2", "3", "4", "5", "6",
"7", "8", "9", "10", "11", "12", "13", "14", "15", "16", "17",
"18", "19", "20", "21", "22", "23", "24", "25", "26", "27", "28",
"29", "30", "31", "32", "33", "34", "35", "36", "37", "38", "39",
"40", "41", "42", "43", "44", "45", "46", "47", "48", "49", "50",
"51", "52", "53", "54", "55", "56", "57", "58", "59", "60", "61",
"62", "63", "64", "65", "66", "67", "68", "69", "70", "71", "72",
"73", "74", "75", "76"), class = "data.frame")

##Not run
#install.packages('eha')
library(eha)
library(survival)

dataexp$status <- rep(1, 76)

aftexp <- aftreg(Surv(Ti,status) ~ vi,  data=dataexp,
    dist="weibull", shape=1)

str(aftexp)
summary(aftexp)
coef(aftexp)

The exponential can be seen as a special case of the weibull distribution with shape = 1. And the help page of aftreg() says precisely to use the weibull with shape = 1 if we want an exponential.


Em 04-08-2012 18:45, hafida escreveu:
Dear R-community,
I have tried to estimate an EXPONENTIEL accelerated failure time(AFT)
power rule model  with time-independent . For that purpose, I have used
the eha package.
Please, consider this example:
   vi      Ti
1  26    5.79
2  26 1579.52
3  26 2323.70
4  28   68.85
5  28  426.07
6  28  110.29
7  28  108.29
8  28 1067.60
9  30   17.05
10 30   22.66
11 30   21.02
12 30  175.88
13 30  139.07
14 30  144.12
15 30   20.46
16 30   43.40
17 30  194.90
18 30   47.30
19 30    7.74
20 32    0.40
21 32   82.85
22 32    9.88
23 32   89.29
24 32  215.10
25 32    1.75
26 32    0.79
27 32   15.93
28 32    3.91
29 32    0.27
30 32    0.69
31 32  100.58
32 32   27.80
33 32   13.95
34 32   53.24
35 34    0.96
36 34    4.15
37 34    0.19
38 34    0.78
39 34    8.01
40 34   31.75
41 34    7.35
42 34    6.50
43 34    8.27
44 34   33.91
45 34   32.52
46 34    3.16
47 34    4.85
48 34    2.78
49 34    4.67
50 34    1.31
51 34   12.06
52 34   36.71
53 34   72.89
54 36    1.97
55 36    0.59
56 36    2.58
57 36    1.69
58 36    2.71
59 36   25.50
60 36    0.35
61 36    0.99
62 36    3.99
63 36    3.67
64 36    2.07
65 36    0.96
66 36    5.35
67 36    2.90
68 36   13.77
69 38    0.47
70 38    0.73
71 38    1.40
72 38    0.74
73 38    0.39
74 38    1.13
75 38    0.09
76 38    2.38
aftexp<-aftreg(Surv(time,status) ~ vi,  data=data.frame(dataexp),
dist="exponentiel")
Error in Surv(time, status) : Time variable is not numeric

aftexp<-aftreg(Surv(Ti,status) ~ vi,  data=data.frame(dataexp),
dist="exponentiel")
Error in Surv(Ti, status) : object 'status' not found
status<- rep(1, 76)
status
  [1] 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
1 1
[39] 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
1 1

cbind(dataexp, status)
    vi      Ti status
1  26    5.79      1
2  26 1579.52      1
3  26 2323.70      1
4  28   68.85      1
5  28  426.07      1
6  28  110.29      1
7  28  108.29      1
8  28 1067.60      1
9  30   17.05      1
10 30   22.66      1
11 30   21.02      1
12 30  175.88      1
13 30  139.07      1
14 30  144.12      1
15 30   20.46      1
16 30   43.40      1
17 30  194.90      1
18 30   47.30      1
19 30    7.74      1
20 32    0.40      1
21 32   82.85      1
22 32    9.88      1
23 32   89.29      1
24 32  215.10      1
25 32    1.75      1
26 32    0.79      1
27 32   15.93      1
28 32    3.91      1
29 32    0.27      1
30 32    0.69      1
31 32  100.58      1
32 32   27.80      1
33 32   13.95      1
34 32   53.24      1
35 34    0.96      1
36 34    4.15      1
37 34    0.19      1
38 34    0.78      1
39 34    8.01      1
40 34   31.75      1
41 34    7.35      1
42 34    6.50      1
43 34    8.27      1
44 34   33.91      1
45 34   32.52      1
46 34    3.16      1
47 34    4.85      1
48 34    2.78      1
49 34    4.67      1
50 34    1.31      1
51 34   12.06      1
52 34   36.71      1
53 34   72.89      1
54 36    1.97      1
55 36    0.59      1
56 36    2.58      1
57 36    1.69      1
58 36    2.71      1
59 36   25.50      1
60 36    0.35      1
61 36    0.99      1
62 36    3.99      1
63 36    3.67      1
64 36    2.07      1
65 36    0.96      1
66 36    5.35      1
67 36    2.90      1
68 36   13.77      1
69 38    0.47      1
70 38    0.73      1
71 38    1.40      1
72 38    0.74      1
73 38    0.39      1
74 38    1.13      1
75 38    0.09      1
76 38    2.38      1

aftexp<-aftreg(Surv(Ti,status) ~ vi,  data=data.frame(dataexp),
dist="exponentiel")
Error in aftreg.fit(X, Y, dist, strats, offset, init, shape, id, control,  :
   exponentiel is not an implemented distribution

aftexp<-aftreg(Surv(time,status) ~ vi,  data=data.frame(dataexp),
dist="exponentiel")
Error in Surv(time, status) : Time variable is not numeric
pleas help me to find a solution to my problem



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