Combine observations by conditions in one dataset

[Chen Wang SF]

Hi everyone,

I need to combine the observations and calculate the sum in my dataset. Please see the example below:

	Year	Brand	Size	Unit	Revenue
1	2010	A	1	100	10000
2	2010	A	1	200	20000
3	2010	B	3	100	30000
4	2011	A	2	100	15000
5	2011	B	1	100	8000
6	2011	B	2	200	26000
7	2011	B	2	200	27000
8	2012	C	1	100	9000
9	2012	C	3	100	40000
10	2012	C	3	300	120000

And I need to combine the observations within the same year, brand, and size, and then sum up their unit and revenue, respectively, so the result should look at this:

	Year	Brand	Size	Unit	Revenue
1	2010	A	1	300	30000
2	2010	B	3	100	30000
3	2011	A	2	100	15000
4	2011	B	1	100	8000
5	2011	B	2	400	53000
6	2012	C	1	100	9000
7	2012	C	3	400	160000

How could I do this in Stata? Thank you!

[Hemanshu Kumar]

See the collapse command.

In particular, you could try

collapse (sum) unit revenue, by(year brand size)

[Chen Wang SF]

See the collapse command.

In particular, you could try

collapse (sum) unit revenue, by(year brand size)

Hi Hemanshu,

You code worked perfectly. Thank you so much for your help!