st: RE: collapsing rows and generating new smaller dataset

[Nick Cox <n.j.cox@durham.ac.uk>]

Assuming that age groups 40-44 ... 75-79 are 1 ... 8 underneath, then you need a new grouping variable that is 

gen new_age_group = cond(age_grp <= 2, 1, cond(age_grp <= 6, 2, 3)) 

or you can do something similar with -recode-. 

The assumption won't be correct, but the principle will be the same. That is, -collapse- needs to be fed a grouping variable created in advance; I don't think there is an easier way to do it. But the difficult ways to do it are all one line long. 

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

Tim Evans

I have a dataset in Stata 11.2 that contains the following:


age_grp	f_pop	m_pop	tot_pop
40-44		7000	7000	14000
45-49		7000	7000	14000
50-54		7000	7000	14000
55-59		6000	6000	12000
60-64		5000	5000	10000
65-69		4000	4000	8000
70-74		3000	3000	6000
75-79		2000	2000	4000

What I want to do is collapse this down so that I have the following three categories which have the sum of each level of age-grp:

age_grp2	f_pop m_pop tot_pop
40-49
50-69
70-79

What I would like to know is how I can collapse the above, but sum the populations of each variable.

I.e 40-49 for f_pop will be the sum of 40-44 and 45-49 and so on.


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