[Traminer-users] Traminer-users Digest, Vol 39, Issue 2

[Arie Riekhoff]

Dear Gilbert,

Thank you so much. I didn't realise that TraMineR would not  
automatically discard those values preceding the "birth date". I have  
recoded my data's begin as well as end dates, which seems to have  
solved my problems!

Best regards,

Aart-Jan


>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Fri, 7 Mar 2014 14:47:46 +0000
> From: Gilbert Ritschard <Gilbert.Ritschard at unige.ch>
> To: Users questions <traminer-users at lists.r-forge.r-project.org>
> Subject: Re: [Traminer-users] Using the process time axis when
> 	converting from	SPELL to STS
> Message-ID:
> 	<66ABD43696E3DB4687E0BB396A76E5F14ECB2E at golf.isis.unige.ch>
> Content-Type: text/plain; charset="us-ascii"
>
> Hi Aart-Jan,
>
> After a quick glance at your code, I notice that you provide  
> 'birthyear' (your 'start' values in pdata) that are greater than the  
> BEGINTIME. This should generate negative ages.  This is probably the  
> source of your problem.
>
> In your example I see that the start time of the first spell is 1  
> for id 1. (Is that a calendar date?). What are the begin time of the  
> first spells for the cases 2, 3, 4 ?
> What does this begin time of observation correspond to ?
>
> Gilbert
>
>
>
>
> -----Original Message-----
> From: traminer-users-bounces at lists.r-forge.r-project.org  
> [mailto:traminer-users-bounces at lists.r-forge.r-project.org] On  
> Behalf Of Arie Riekhoff
> Sent: Wednesday, March 05, 2014 14:13
> To: traminer-users at r-forge.wu-wien.ac.at
> Subject: [Traminer-users] Using the process time axis when  
> converting from SPELL to STS
>
> Hello!
>
> The TraMineR package has been doing a wonderful job with my data and  
> it's a real pleasure to work with it, even as a beginner in R. I  
> have just run into a problem with the process axis function in the  
> seqformat command and I haven't managed to figure out what I'm doing  
> wrong.
>
> My data comes in SPELL format and I want to convert it to STS before  
> creating a sequence object. Following instruction from the TraMineR  
> user's guide this work very nicely if I select process = FALSE.
> However, I need to use the process time axis, because I'm working  
> with a cohort of 3 consecutive birth years and I want to start  
> counting from the year in which they reach a specific age and then  
> follow them for the next 10 years (i.e. 120 months). My data starts  
> in 1999 and registers statuses per month. I have recoded the dates,  
> so that January 1999 is 1, February 1999 is 2, etc. I want to start  
> the time axis for the respondents from the 3 consecutive birth years  
> at t = 1 (year 1), t = 13 (year 2) and t = 25 (year 3). I have  
> imported a separate file with the id's of the respondents and the  
> different start times.
>
> So, my command was the following:
>
>> wr.sts.process <- seqformat (wr, id = "ID", begin = "BEGINTIME", end =
>> "ENDTIME", status = SOCECST_rec", from = "SPELL", to = "STS", process
>> = TRUE, pdata = starttime, pvar =c("ID", "start"), limit =
>> 120)
>     [>] SPELL data converted into 2088 STS sequences
>
> But it results in missing values (NA) for almost each status.
>
> My wr dataframe with spell data looks something like this:
>
>> wr [1:5,]
>
>      ID    BEGINTIME    ENDTIME    SOCECST_rec
> 1   1             1         16             1
> 2   1             17        18             4
> 3   1             19        20             4
> 4   1             21        21             4
> 5   1             22        22             3
>
> I had followed the user guide's advice to convert the status  
> variable into an integer.
>
> And my starttime dataframe like this:
>
>> starttime [1:5,]
>
>      ID   start
> 1    1      13
> 2    2      13
> 3    3      25
> 4    4       1
> 5    5      25
>
> I also tried converting into converting into a sequence object with  
> the seqdef() function directly from spell data, but run into the  
> same problem ([!] sequence with index: 1,2,3 etc contains only  
> missing values).
>
> Like I wrote, when I use process = FALSE, both seqformat and seqdef  
> work perfectly well, so it's not the wr data that's the problem. I  
> guess I'm doing something wrong with the process time axis.
>
> Someone might have asked a similar question here before, but I  
> couldn't find any definite answers anywhere. I hope that someone can  
> point me in the right direction or give me a hint as to the solution  
> of my problem!
>
> Thanks in advance,
>
> Aart-Jan
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> End of Traminer-users Digest, Vol 39, Issue 2
> *********************************************