[R] How to turn individual consecutive information into survival objects?

[Guido van Steen]

Dear R List, 

I have a dataset with the following structure:  

"""personal_id, p_0, p_1, p_2, .... , p_36, p_37 
1, NA, 1, 4, .... , 1, NA 
2, NA, NA, NA, .... , 4, NA 
.
.
.
6020, NA, 3, 3, ...., NA, NA
6021, NA, 2, 2, ...., 4, NA
"""

I used some made-up data. It is just meant to show the structure of the dataset. 

The variables of interest are p_0, ... p_37. They represent types of activity of the 6021 persons interviewed in 38 consecutive period. 

The values for p_0 and p_37 are coded as follows: 
1 = self-employed 
2 = employed 
3 = in training 
4 = unemployed 
NA = no information available  

p_0 is the period before p_1. This period was just before the survey, so that none of the individuals were interviewed in this period. 

p_37 is the period after p_36. This period was just after the survey, so that none of the individuals were interviewed in this period. 

I would like to transform this dataset into information on the lenght of the first spell of unemployment. (If there are multiple spells I would just like to use the first one.) 

My question is how can I convert the records in this dataset into survivul objects - "Surv()" - so that they can be used with a function like "coxph()".

Could anyone give me a pointer to a function that performs this specific conversion? 

Thanks in advance! 

Guido 



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