## re-base a series

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Occasional Contributor
Posts: 6

# re-base a series

Hi,

Time series data (CPI, for example) are often indexed to a specific base year such that the value in that year is 1 (or 100) and the values in other years are expressed as ratios to the base year value.  I would like to re-base (or re-index) my series to a new base year which simply involves dividing each value by the value in my desired base year.  The difficulty is that for the early years, I need to know the value in that later, base year.  Does anyone know if there's a simple way to do this (i.e. without getting in to macro programming)?

Thank you all!

Accepted Solutions
Solution
‎07-18-2017 09:48 AM
Super Contributor
Posts: 293

## Re: re-base a series

Posted in reply to ChrisBrooks

Hello,

An other possible solution :

``````data want;
retain base;

if _N_=1 then do;
set have (where=(year=2004));
base=val;
end;

set have;
index_val=val/base;

drop base;
run;``````

All Replies
Valued Guide
Posts: 533

## Re: re-base a series

Posted in reply to flyingbear

You simply select the base year value into a macro variable first and use it in your data step like this

``````data have;
input year val;
datalines;
2000 50
2001 60
2002 70
2003 75
2004 90
2005 100
2006 120
2007 150
2008 155
2009 200
;
run;

/* Store the base year value in a macro variable */

proc sql;
select val into :base_val
from have
where year =2004;
quit;

data want;
set have;
index_val=val/&base_val;
run;``````
Solution
‎07-18-2017 09:48 AM
Super Contributor
Posts: 293

## Re: re-base a series

Posted in reply to ChrisBrooks

Hello,

An other possible solution :

``````data want;
retain base;

if _N_=1 then do;
set have (where=(year=2004));
base=val;
end;

set have;
index_val=val/base;

drop base;
run;``````

Occasional Contributor
Posts: 6

## Re: re-base a series

Thanks! This is very instructive regarding the data step -- helpful for this problem and in the future.
Occasional Contributor
Posts: 6

## Re: re-base a series

Posted in reply to ChrisBrooks

Thanks very much!

☑ This topic is solved.

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