Dear StataList Members,

I am trying to conduct a surival anaylsis using the data I placed here.

The code I use is here: stset age_months , failure(monthly_duration==0)

age_months is the age of children given in months. It is my time variable. It starts from 0. It ends in 59.
monthly_duration is a dichotomous variable that indicates whether the child is still breastfed or not. If 1, the child is still breatfed. If 0, not still breastfed. It is my event variable.

When I run this code:

stset age_months , failure(monthly_duration==0), I get the notification :
207691 total observations
7625 observations end on or before enter()

I know why this is the case. In my data, 7625 of observations are children who are 0 month old (age_months=0), and all of those 7625 children are still brastfed. There is no exception.
That is, all those 7625 children take the value of 1 for their monthly_duration variable.

My question is here: Can I proceed my analysis? Is that true? Because now the 7625 children are lost. My N is 200066 rahther than 207691 (the difference is 7625). If it is not true, what should I do?

Thank you very much.



clear
input float(age_months monthly_duration) double M4_1 str15 CASEID float age_months2
0 1 20 " 10110 2" 21
1 1 20 " 10110 2" 21
2 1 20 " 10110 2" 21
3 1 20 " 10110 2" 21
4 1 20 " 10110 2" 21
5 1 20 " 10110 2" 21
6 1 20 " 10110 2" 21
7 1 20 " 10110 2" 21
8 1 20 " 10110 2" 21
9 1 20 " 10110 2" 21
10 1 20 " 10110 2" 21
11 1 20 " 10110 2" 21
12 1 20 " 10110 2" 21
13 1 20 " 10110 2" 21
14 1 20 " 10110 2" 21
15 1 20 " 10110 2" 21
16 1 20 " 10110 2" 21
17 1 20 " 10110 2" 21
18 1 20 " 10110 2" 21
19 1 20 " 10110 2" 21
20 1 20 " 10110 2" 21
21 0 20 " 10110 2" 21
0 1 17 " 102 3 2" 59
1 1 17 " 102 3 2" 59
2 1 17 " 102 3 2" 59
3 1 17 " 102 3 2" 59
4 1 17 " 102 3 2" 59
5 1 17 " 102 3 2" 59
6 1 17 " 102 3 2" 59
7 1 17 " 102 3 2" 59
8 1 17 " 102 3 2" 59
9 1 17 " 102 3 2" 59
10 1 17 " 102 3 2" 59
11 1 17 " 102 3 2" 59
12 1 17 " 102 3 2" 59
13 1 17 " 102 3 2" 59
14 1 17 " 102 3 2" 59
15 1 17 " 102 3 2" 59
16 1 17 " 102 3 2" 59
17 1 17 " 102 3 2" 59
18 0 17 " 102 3 2" 59
19 0 17 " 102 3 2" 59
20 0 17 " 102 3 2" 59
21 0 17 " 102 3 2" 59
22 0 17 " 102 3 2" 59
23 0 17 " 102 3 2" 59
24 0 17 " 102 3 2" 59
25 0 17 " 102 3 2" 59
26 0 17 " 102 3 2" 59
27 0 17 " 102 3 2" 59
28 0 17 " 102 3 2" 59
29 0 17 " 102 3 2" 59
30 0 17 " 102 3 2" 59
31 0 17 " 102 3 2" 59
32 0 17 " 102 3 2" 59
33 0 17 " 102 3 2" 59
34 0 17 " 102 3 2" 59
35 0 17 " 102 3 2" 59
36 0 17 " 102 3 2" 59
37 0 17 " 102 3 2" 59
38 0 17 " 102 3 2" 59
39 0 17 " 102 3 2" 59
40 0 17 " 102 3 2" 59
41 0 17 " 102 3 2" 59
42 0 17 " 102 3 2" 59
43 0 17 " 102 3 2" 59
44 0 17 " 102 3 2" 59
45 0 17 " 102 3 2" 59
46 0 17 " 102 3 2" 59
47 0 17 " 102 3 2" 59
48 0 17 " 102 3 2" 59
49 0 17 " 102 3 2" 59
50 0 17 " 102 3 2" 59
51 0 17 " 102 3 2" 59
52 0 17 " 102 3 2" 59
53 0 17 " 102 3 2" 59
54 0 17 " 102 3 2" 59
55 0 17 " 102 3 2" 59
56 0 17 " 102 3 2" 59
57 0 17 " 102 3 2" 59
58 0 17 " 102 3 2" 59
59 0 17 " 102 3 2" 59
0 1 24 " 10217 1" 41
1 1 24 " 10217 1" 41
2 1 24 " 10217 1" 41
3 1 24 " 10217 1" 41
4 1 24 " 10217 1" 41
5 1 24 " 10217 1" 41
6 1 24 " 10217 1" 41
7 1 24 " 10217 1" 41
8 1 24 " 10217 1" 41
9 1 24 " 10217 1" 41
10 1 24 " 10217 1" 41
11 1 24 " 10217 1" 41
12 1 24 " 10217 1" 41
13 1 24 " 10217 1" 41
14 1 24 " 10217 1" 41
15 1 24 " 10217 1" 41
16 1 24 " 10217 1" 41
17 1 24 " 10217 1" 41
end
label values M4_1 M4_1
[/CODE]