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# RE: st: creating variable summarizing for each individual properties of other members of a group at t-1

 From Nick Cox To "'statalist@hsphsun2.harvard.edu'" Subject RE: st: creating variable summarizing for each individual properties of other members of a group at t-1 Date Thu, 19 May 2011 13:34:33 +0100

```That's much clearer to me, or rather I now realise some stupid misunderstandings of your earlier posts.

I've used different variable names. I now suggest this.

bysort ind_id (yearmonth) : gen ind_score2 = min(sum(ind_entry), 1)
egen all_score2 = total(ind_score2), by(yearmonth)
replace all_score2 = all_score2 - ind_score2
bysort ind_id (yearmonth) : gen prevscore2 = all_score2[_n-1]

Notable that the code, which reproduces your CORRECT, is much simpler than earlier bad versions.

Nick
n.j.cox@durham.ac.uk

I will try to explain why the suggested code below does not solve my second problem and what it gets wrong. The suggested code below does not solve my second problem because the all_score for a given ind_id includes ind_entry = 1 contribution for that same ind_id. I need the variable to sum the number of peer entrants (sum of unique ind_ids excluding the focal ind_id) over yearmonths for each ind_id. Once an ind_d has experienced ind_entry=1, the ind_id is considered an entrant and subsequent ind_entries = 1 for that ind_id does not change that. Given the code below, an ind_id gets an all_score and prevscore that includes their own entry. It seems problematic to me to consider an ind_id to be a peer to him or herself.

See the resulting output below. I have entered an additional column to the right indicating the correct prevscore for each ind_id.

year    month    yearmonth    ind_id    ind_entry    ind_score    all_score    prevscore    CORRECT prevscore
2003    10       10           2         0            0            1
2003    11       11           2         0            0            1            1            1
2003    12       12           2         0            0            1            1            1
2004    1        13           2         0            0            1            1            1
2004    2        14           2         1            1            1            1            1
2004    3        15           2         0            0            2            1            1
2003    10       10           4         1            1            0
2003    11       11           4         0            0            1            0            0
2003    12       12           4         1            0            1            1            0
2004    1        13           4         0            0            1            1            0
2004    2        14           4         0            0            2            1            0
2004    3        15           4         0            0            2            2            1

Sincerely,

> From: n.j.cox@durham.ac.uk
> To: statalist@hsphsun2.harvard.edu
> Date: Wed, 18 May 2011 18:36:37 +0100
> Subject: RE: st: creating variable summarizing for each individual properties of other members of a group at t-1
>
> My code
>
> bysort ind_id (yearmonth) : gen ind_score = sum(ind_entry)
> by ind_id : replace ind_score = ind_score == 1 & ind_score[_n-1] != 1
> sort yearmonth
> gen all_score = sum(ind_score)
> by yearmonth : replace all_score = all_score[_N]
> replace all_score = all_score - ind_score
> bysort ind_id (yearmonth) : gen prevscore = allscore[_n-1]
>
> was certainly intended to solve your second problem. I've not tested it. Are you saying it doesn't? And if it doesn't what does it get wrong?
>
> Nick
> n.j.cox@durham.ac.uk
>
>
> Thank you Nick and Jorge for your suggestions. They were very helpful, and I am very grateful.
>
> Jorge, your suggested code below worked perfectly for my "first" variable.
>
> I am still struggling with my "second" variable. In the "second" variable, I am trying to create a variable that for each ind_id counts the total number of other ind_ids, excluding the focal ind_id, in the dataset that have experienced ind_entry =1 at least once up until and including yearmonth -1. In other words, I am trying to create a variable that for each individual tracks the number of other entrants in the dataset up until and including yearmonth -1. I am trying to track ind_ids that have entered, not how many times they have entered.
>
> Any and all input on this problem would be very much appreciated.

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