Finding Market Shares

[Muhammad Arslan Iqbal]

Hi all,

I have a data in the following format. I need to calculate the market share where market share would be simply percentage of sales of the brand in the given year and market. For example, A in the table should be Sales of Brand 1 in year 2000 and market 1 to Total sales in year 2000 and market 1. This should be 56 / (56 + 25). Similarly, B should be (34 / (34+54+43) ). Finally, C should be (47/ (47+43)). Any coding help for such problem is much appreciated.

Year	Market	Brand	Sales	Market Share
2000	1	1	56	A
2001	1	1	34	B
2002	1	1	45
2001	1	2	54
2002	1	2	46
2000	1	3	25
2001	1	3	43
2002	1	3	41
2000	2	1	47	C
2001	2	1	65
2002	2	1	62
2001	2	2	21
2002	2	2	43
2000	2	3	43

[Chen Samulsion]

bysort year market: egen tsales=total(sales)
gen marketshare=sales/tsales*100

[Fei Wang]

Muhammad, you may try the following code.

bys year market: egen total_sales = total(sales)
gen share = sales / total_sales

[Muhammad Arslan Iqbal]

Thank you so much Chen and Fei, that was helpful.

[Nick Cox]

Here is a more direct solution. As requested in the FAQ Advice #12, please use dataex .

* Example generated by -dataex-. For more info, type help dataex
clear
input int year byte(market brand sales)
2000 1 1 56
2001 1 1 34
2002 1 1 45
2001 1 2 54
2002 1 2 46
2000 1 3 25
2001 1 3 43
2002 1 3 41
2000 2 1 47
2001 2 1 65
2002 2 1 62
2001 2 2 21
2002 2 2 43
2000 2 3 43
end

egen wanted = pc(sales), by(year market)
l, sepby(year market)

     +------------------------------------------+
     | year   market   brand   sales     wanted |
     |------------------------------------------|
  1. | 2000        1       1      56    69.1358 |
  2. | 2000        1       3      25    30.8642 |
     |------------------------------------------|
  3. | 2000        2       1      47   52.22222 |
  4. | 2000        2       3      43   47.77778 |
     |------------------------------------------|
  5. | 2001        1       1      34    25.9542 |
  6. | 2001        1       2      54   41.22137 |
  7. | 2001        1       3      43   32.82443 |
     |------------------------------------------|
  8. | 2001        2       1      65    75.5814 |
  9. | 2001        2       2      21    24.4186 |
     |------------------------------------------|
 10. | 2002        1       1      45   34.09091 |
 11. | 2002        1       2      46   34.84848 |
 12. | 2002        1       3      41   31.06061 |
     |------------------------------------------|
 13. | 2002        2       1      62   59.04762 |
 14. | 2002        2       2      43   40.95238 |
     +------------------------------------------+