Posted by
Art Kendall on
URL: http://spssx-discussion.165.s1.nabble.com/Calculating-percent-change-using-panel-data-set-tp5713457p5713505.html
It is calculating the percent change for a one year
period to the next (since1yrago) compounded over a 2 year
period (since2yrago), and compounded over a 3 year period
(since3yrago.
If that is the only variable you want the COMPUTE for is
"demo1yrago" It is more intuitive IFF you are only interested in a
one year change.
However, to find the percent change compounded over more than one
year you need to use the formulae that take compounding into
account.
for the demo syntax simply use the LIST command so it only lists the
variables you are interested in. Put an asterisk to the left of the
one you are not interested in.
If you only want the 1 year change simply ignore the other columns
in the data file.
In the aggregated file again simply ignore the other columns.
Remember the aggregated results are only meaningful if there is no
missing data.
NOTE that in the simulated data Hospital #3 has no 2009 data
record. The actual aggregated numbers in the aggfile that would
involve 2009 are invalid.
if you have no missing data the numbers in those positions would be
valid. You can ignore the other columns if you wish.
2008 4600.00
2009 3625.00 x
2010 4702.00 29.7% 1.1%
2011 4768.00 1.4% x 1.2%
If I am misinterpreting your question, please explain in more
detail.
Is there missing data?
Are you interested in each hospital or only the aggregated data?
data list list /hospital (f1) year(f4) unemployed (f4).
begin data.
1 2008 1000
1 2009 1010
1 2010 1020
1 2011 1031
2 2008 1000
2 2009 990
2 2010 980
2 2011 970
3 2008 1000
3 2010 1020
3 2011 1031
4 2008 1000
4 2009 1010
4 2010 1020
4 2011 1031
5 2008 500
5 2009 525
5 2010 552
5 2011 580
6 2008 100
6 2009 90
6 2010 110
6 2011 125
end data.
numeric since1yrago since2yrago since3yrago(pct7.1).
do repeat periods = 1 to 3/ since= since1yrago to since3yrago.
do if hospital eq lag(hospital,periods) and year eq
lag(year,periods)+periods.
compute since = 100* ( ( ( (unemployed/lag(unemployed,periods) )
**(1/periods) ) )-1).
end if.
end repeat.
list.
list /variables = hospital year since1yrago since2yrago since3yrago.
* calculate overall rates ASSUMING NO MISSING DATA.
*NOTE in the simulated data above Hospital #3 has NO 2009 data.
sort cases by year.
dataset declare aggfile.
aggregate outfile=aggfile /break= year
/sum_unemployed = sum(unemployed).
dataset activate aggfile.
numeric since1yrago since2yrago since3yrago(pct7.1).
do repeat periods = 1 to 3/ since= since1yrago to since3yrago.
compute since = 100* ( ( (
(sum_unemployed/lag(sum_unemployed,periods) ) **(1/periods) ) )-1).
end repeat.
list.
list /variables = year sum_unemployed since1yrago.
Art Kendall
Social Research Consultants
On 6/3/2012 4:24 PM, Ginny Razo wrote:
Hi
Art,
Sorry
to bother you again. After speaking with my chair, he has
advised me to calculate the percent change by year. So for
example, it would be more beneficial to calculate the
percent change from 2005-2006 and from 2006-2007. Is this
what this is calculating? If it is calculating the percent
change from 2005 for 1 year, then 2 years than 3 years, I
will need to modify it.
Any
assistance you can provide is greatly appreciated!
Kind
Regards,
Ginny
Razo
From:
Art Kendall [[hidden email]]
Sent: Saturday, June 02, 2012 8:54 AM
To: Virginia Razo
Cc: [hidden email]
Subject: Re: [SPSSX-L] Calculating percent change
using panel data set
if you
already have the data in an SPSS file GET that file. Then
substitute your variable names for the names in my example
syntax.
Begin data ... end data is used in the demo syntax because
system files (*.sav) cannot be attached to post to the
discussion list.
Also the demo variable won't be needed once you see that you
get the same result for demo1yrago and since1yrago.
Recall that numerators and denominators need to be summed
separately to get overall rates or percents.
Get file = . . .
numeric since1yrago
since2yrago since3yrago(pct7.1).
do repeat periods = 1 to 3/ since= since1yrago to
since3yrago.
do if hospital eq lag(hospital,periods) and year eq
lag(year,periods)+periods.
compute since = 100* ( ( (
(unemployed/lag(unemployed,periods) ) **(1/periods) )
)-1).
end if.
end repeat.
* calculate overall rates ASSUMING NO MISSING DATA.
sort cases by year.
dataset declare aggfile.
aggregate outfile=aggfile /break= year
/sum_unemployed = sum(unemployed).
dataset activate aggfile.
numeric since1yrago since2yrago since3yrago(pct7.1).
do repeat periods = 1 to 3/ since= since1yrago to since3yrago.
compute since = 100* ( ( (
(unemployed/lag(unemployed,periods) ) **(1/periods) ) )-1).
end repeat.
list.
_ if you have any missing data, medians would be meaningful as
summary statistics, overall rates based on sums would not be
meaningful.
Art Kendall
Social Research Consultants
On 6/2/2012 11:13 AM, Virginia Razo wrote:
Hello Art,
Thanks for taking your time to respond to my cry out for help. The data I
provided was just an example and I actually have more than 8000
observations. How can I enter the begining and end of data list without
typing every observations hospital by year?
Kind Regards,
Ginny
--
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Art Kendall
Social Research Consultants