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02-07-2013 07:47 AM

Dear all,

I have a dataset with the following variables:

gvkey = firm identification code

fyear = financial year (since year 1950)

sic3 = industry classification code based on the first 3-digit

zipcode = US zipcode

I wish to calculate the following variable:

**Cluster age**, measured as the number of years since the first firm in a given industry (sic3) was founded in the cluster, where

Cluster, is measured as 50 miles radius from the firm (gvkey) (note: 50 miles radius can be calculated by using the zipcode of the firm), for a given financial year (fyear) in a particular industry (sic3).

In order to calculate cluster age, I must first to know the year that the first firm (in the same industry - SIC3) was found within 50 miles radius from the firm (gvkey), which is also in the same industry as the firm (gvkey).

Mathematical formula to calculate **cluster age** = fyear - firstyear + 1, where firstyear = the year that the first firm (in the same industry - SIC3) was found within 50 miles radius from the firm (gvkey).

I have no idea on how to calculate this variable.

Hope to get any suggested SAS code which can help me to calculate the cluster age efficiently.

Thank you in advance.

Regards,

mspak

Accepted Solutions

Solution

02-07-2013
08:20 AM

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Posted in reply to mspak

02-07-2013 08:20 AM

You might have a better source for lat/long than sashelp...but this might get you started: (yeah for spherical geometry)

%let pi180=0.0174532925199433;

proc sort in=tmp.testdata out=work.testdata;

by gvkey fyear;

run;

proc sort in=tmp.testdata out=work.testdata_srt nodupkey;

by gvkey;

run;

proc sql;

create table work.testdata_geo as

select

t1.gvkey

,t1.fyear

,t1.sic3

,t1.zipcode

,t2.y as latitude_y

,t2.x as longitude_x

from

work.testdata_srt t1

left outer join sashelp.zipcode t2

on input(t1.zipcode,5.)=t2.zip;

alter table work.testdata_geo add constraint pk_tg primary key (gvkey);

create table work.clusters as

select

t1.sic3

,t1.zipcode

,min(t2.fyear) as Cluster_Start

from

work.testdata_geo t1, work.testdata_geo t2

where

t1.sic3=t2.sic3

and (7921.6623*arsin(sqrt((sin((&pi180*t2.latitude_y - &pi180*t1.latitude_y)/2))**2 +

cos(&pi180*t1.latitude_y)*cos(&pi180*t2.latitude_y)*(sin((&pi180*t2.longitude_x - &pi180*t1.longitude_x)/2))**2))) < 50

group by t1.sic3, t1.zipcode;

create table want as

select

t1.*

,t2.cluster_start

,t1.fyear - t2.cluster_start + 1 as Cluster_Age

from

tmp.testdata t1

left outer join work.clusters t2

on t1.sic3=t2.sic3

and t1.zipcode=t2.zipcode;

quit;

All Replies

Solution

02-07-2013
08:20 AM

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Posted in reply to mspak

02-07-2013 08:20 AM

You might have a better source for lat/long than sashelp...but this might get you started: (yeah for spherical geometry)

%let pi180=0.0174532925199433;

proc sort in=tmp.testdata out=work.testdata;

by gvkey fyear;

run;

proc sort in=tmp.testdata out=work.testdata_srt nodupkey;

by gvkey;

run;

proc sql;

create table work.testdata_geo as

select

t1.gvkey

,t1.fyear

,t1.sic3

,t1.zipcode

,t2.y as latitude_y

,t2.x as longitude_x

from

work.testdata_srt t1

left outer join sashelp.zipcode t2

on input(t1.zipcode,5.)=t2.zip;

alter table work.testdata_geo add constraint pk_tg primary key (gvkey);

create table work.clusters as

select

t1.sic3

,t1.zipcode

,min(t2.fyear) as Cluster_Start

from

work.testdata_geo t1, work.testdata_geo t2

where

t1.sic3=t2.sic3

and (7921.6623*arsin(sqrt((sin((&pi180*t2.latitude_y - &pi180*t1.latitude_y)/2))**2 +

cos(&pi180*t1.latitude_y)*cos(&pi180*t2.latitude_y)*(sin((&pi180*t2.longitude_x - &pi180*t1.longitude_x)/2))**2))) < 50

group by t1.sic3, t1.zipcode;

create table want as

select

t1.*

,t2.cluster_start

,t1.fyear - t2.cluster_start + 1 as Cluster_Age

from

tmp.testdata t1

left outer join work.clusters t2

on t1.sic3=t2.sic3

and t1.zipcode=t2.zipcode;

quit;

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Posted in reply to DBailey

02-07-2013 09:10 PM

Thanks DBailey for the code.

I always used zipcitydistance function in SAS to calculate the geographical distance.

Can the following

(7921.6623*arsin(sqrt((sin((&pi180*t2.latitude_y - &pi180*t1.latitude_y)/2))**2 +

cos(&pi180*t1.latitude_y)*cos(&pi180*t2.latitude_y)*(sin((&pi180*t2.longitude_x - &pi180*t1.longitude_x)/2))**2))) < 50

replaced with

.<zipcitydistance<=50?

Thank you.

Regards,

mspak

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Posted in reply to mspak

02-08-2013 08:29 AM

well...knowing that sas had a function to do that would have saved me countless hours of scanning my old math books several years ago when I needed the same calculation.

yes it works fine.