Re: st: Finding patterns of consecutive number

[Marshall Garland <marshall.w.garland@gmail.com>]

Hi Nick-

This is exactly what I needed.

Thanks so much for your help and prompt reply.

Cheers,

-mwg

On Wed, Apr 25, 2012 at 8:24 PM, Nick Cox <njcoxstata@gmail.com> wrote:
> I think of your problem as defining spells of consecutive integers, so
> that a spell starts with the first observation in each panel or if the
> previous value was not one fewer.
>
> bysort id (year) : gen progress = string(test) if _n == 1 | (test -
> test[_n-1] != 1)
> by id : replace progress = progress[_n-1] + string(test) if missing(progress)
>
> Dealing with spells: see also -tsspell- (SSC) or
>
> SJ-7-2  dm0029  . . . . . . . . . . . . . . Speaking Stata: Identifying spells
>        . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  N. J. Cox
>        Q2/07   SJ 7(2):249--265                                 (no commands)
>        shows how to handle spells with complete control over
>        spell specification
>
> By the way, as the putative author of -tostring-, I note that it is
> overkill here. The -string()- function is all you need.
>
> Nick
>
> On Wed, Apr 25, 2012 at 11:47 PM, Marshall Garland
> <marshall.w.garland@gmail.com> wrote:
>
>> I have panel student testing data spanning six years. Each year, I
>> have a unique student and student test level and outcome. Testing
>> levels across years are not necessarily consecutive, nor are years.
>> For each student, in each year, I'd like to create a variable that
>> captures the longitudinal test progression for each student, in each
>> year. However, for each year, I'd like the maximum consecutive test
>> progression, without disruptions. This maximum test progression should
>> only be calculated for consecutive years, too.
>>
>> I've posted my data at the end of this message, which will help
>> describe my objective. For student A, in 2008/09, her test progression
>> is 6543, since she had 4 consecutive years of test data. This is
>> perfect. Student B, however, in 2008/09, has a test progression of
>> 7643. However, I only want to record, for student B, the maximum
>> consecutive test progression, which is 76 and ignore the 43. The 43
>> progression will be captured in the corresponding year (2006/07).
>>
>> I can't figure out a way to adjust for this discontinuity. I've tried
>> a number of things, including this. But, this still captures repeated
>> test levels across years (student C below, in 2008/09).
>>
>> Thanks for help in advance.
>>
>> Cheers,
>>
>> -mwg
>>
>> /****************************************************
>> bys research_id: gen test_t=d.test_level_2
>> bys research_id: egen max_test_t=max(test_t)
>>
>> ///group creation for consecutive runs
>> forvalues i=0/6 {
>>        gen group_`i'=.
>>        bys research_i (sch_yr): replace group_`i'=test_level_2[_n-`i'] if
>> max_test_t==1 & test_t==1
>>        tostring group_`i', replace
>>        replace group_`i'="" if group_`i'=="."
>> }
>>
>> egen group_ty_cons=concat(group_0- group_6)
>> tab group_ty_cons
>> /**************************************************************
>>
>> Here's my data:
>> student year    test_level      progression
>> A       2005/06 3
>> A       2006/07 4       43
>> A       2007/08 5       543
>> A       2008/09 6       6543
>> B       2005/06 3
>> B       2006/07 4       43
>> B       2007/08 6       643
>> B       2008/09 7       7643
>> C       2005/06 6
>> C       2006/07 7       76
>> C       2007/08 8       876
>> C       2008/09 8       8876
>
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