Compare values across rows within observation

[LI LIU]

Hi,
My datasets are like following forms:
Inventorid patentyear firmid
3930988 2000 13928
3930988 2001 13928
3930988 2002 15892
3890212 2001 15892
3890212 2001 15892

I'm trying to compare firmid for the same inventor and generate a variable move = 1 if firmid != firmid in the previous rows. The desired results is as follows. For example, for inventor 3930988, he is regarded as move = 1 when the firmid change (15892 VS 13928).
NOTE that, comparison of the firms only within observations. For example, for inventor 3930988, compare firmid within the first 3 rows. for Inventor 3890212, compare within the last two rows. Many thanks if you could provide any suggestions!

Inventorid patentyear firmid move
3930988 2000 13928 0
3930988 2001 13928 0
3930988 2002 15892 1
3890212 2001 15892 0
3890212 2001 15892 0

[Wouter Wakker]

How would you want your move variable to be in this case?

Inventorid patentyear firmid
3930988 2000 13928
3930988 2001 13928
3930988 2002 15892
3930988 2003 13928

[LI LIU]

How would you want your move variable to be in this case?

Inventorid patentyear firmid
3930988 2000 13928
3930988 2001 13928
3930988 2002 15892
3930988 2003 13928

Hi Wouter,
I would like use to identify inventor who change his job. If move = 1, it implies that inventor patent in two different firms within the same year or across years. Therefore, it is implied that this inventor change his job (move to another company). Ultimately, I will extract the following information for inventors who move:

Inventorid year firmid_before_move firmid_after_move
3930988 2002 13928 15982

[Wouter Wakker]

Yes, I got that from #1.

My point is, what happens when an inventor moves back to a firm where he was previously, before moving to another firm. (see #2) Do you still want to code it as being a job change? If so, or if this doesn't happen at all:

bysort Inventorid (patentyear): gen wanted = firmid != firmid[_n-1] & _n > 1

[LI LIU]

Yes, I got that from #1.

My point is, what happens when an inventor moves back to a firm where he was previously, before moving to another firm. (see #2) Do you still want to code it as being a job change? If so, or if this doesn't happen at all:

bysort Inventorid (patentyear): gen wanted = firmid != firmid[_n-1] & _n > 1

Hi Wouter,
Many thanks for your kind help! It works quite well. For those who move back to the orignal firm, yes they are coded as a job change. And I infer that the code also code as they change a job when move back to orignal firm. Thanks pretty much!

[LI LIU]

Yes, I got that from #1.

My point is, what happens when an inventor moves back to a firm where he was previously, before moving to another firm. (see #2) Do you still want to code it as being a job change? If so, or if this doesn't happen at all:

bysort Inventorid (patentyear): gen wanted = firmid != firmid[_n-1] & _n > 1

By the way, if the rule changes, say, the event that inventor moves back to the orignal firm will not be refered as a mobility event. How will the code change?

I have thought about this one, but not hundred percent sure:
forvalues i = 1/50 {
bysort Inventorid (patentyear): gen wanted = firmid != firmid[_n-'i'] & _n > 1
}

[Wouter Wakker]

bysort Inventorid (patentyear): gen wanted = firmid != firmid[_n-1] & _n > 1
bysort Inventorid firmid (patentyear): replace wanted = 0 if _n > 1

[LI LIU]

bysort Inventorid (patentyear): gen wanted = firmid != firmid[_n-1] & _n > 1
bysort Inventorid firmid (patentyear): replace wanted = 0 if _n > 1

many thanks Wouter!