Re: st: weekly minus monthly data

[Nick Cox <njcoxstata@gmail.com>]

If you were worried about efficiency, you need not -generate- the  
variable -diff- but on other grounds you do need it to check what you  
have done.

Nick

On 13 Sep 2011, at 15:17, Nikolaos Kanellopoulos <nkkanel@yahoo.gr>  
wrote:

> Dear all,
>
> I have information regarding the month and year during which a  
> rental contract was signed (sign_year & sign_month) and the year and  
> week of the survey (surv_year & surv_week). I want to identify the  
> contracts which were signed in less than three months from the week  
> of the survey. My approach is to convert everything in monthly data  
> and calculate the difference using the following:
>
> gen date1 = mofd(dofw(yw( surv_year,surv_week )))
> gen date2 = ym( sign_year , sign_month)
> gen diff = date1 - date2
> keep if diff<4
>
> Two questions:
> 1)     Is my approach correct. For a few individuals I get negative  
> values. I suppose that this can occur if the week of the survey is  
> within the month that the contract was signed.
>
> 2)     Ii my approach is correct is there a better (more efficient)  
> way to do this?
>
> Kind regards
> Nikos
>
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