# st: RE: sum and product

 From "Nick Cox" To Subject st: RE: sum and product Date Mon, 9 Dec 2002 14:55:33 -0000

```Rodrigo Briceņo

> I need to make some calculations that are common for me,
> but utilizing Excel.
> I have two variables (each with 300,000 observations):
> Number of discharges
> and Relative Weight. I need to make this.
>
> 1. Multiply the number of discharges by the relative weight
> 2. Sum all these results obtained in 1.
> 3. Divide an amount of expenditures between this sum
> results (obtained in
> 2), so I can estimate the value of each of the relative points.
>
>
> I never have been used Stata to perform arithmetic
> operations, so excuse me
> if I look so dumb.
>

-egen- includes a -pc()- function which
takes an expression and which can optionally yield
proportions.

Thus

. egen prop = pc(weight * whatever), prop

yields a variable prop which sums to 1.

Otherwise, see help on -operators-,
help on -functions- and help on -egen-.

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

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```