st: RE: Calculating growth rates in a panel dataset

["Martin Weiss" <martin.weiss1@gmx.de>]

- bys id: g salesgrowth=(sales[_n]-sales[_n-1])/sales[_n-1]-


HTH
Martin

-----Original Message-----
From: owner-statalist@hsphsun2.harvard.edu
[mailto:owner-statalist@hsphsun2.harvard.edu] On Behalf Of Marcus Keupp
Sent: Monday, October 13, 2008 9:17 AM
To: statalist@hsphsun2.harvard.edu
Subject: st: Calculating growth rates in a panel dataset

Dear Statalisters,

please forgive me if the following question seems obvious to you. I have 
checked the Statalist
archive and FAQs but answers but found none. My problem is one of data 
manipulation in a large
panel dataset. The data ave the following form ("Time of measurement" 
refers to the six points in time when the data were collected,
for research design reasons I only use information from periods 3-6)

Panel ID (firm)        Time of measurement                      Sales 
103                                3                        3.3million 
103                                4                        6.0million 
103                                5                        8.2million 
103                                6                        8.9million 
104                                3                        45.2million 
104                                4                        46.5million 
104                                5                        43.2million
104                                          6 37.2million 

and so on for all panel IDs. What I want to do is to calculate the sales 
growth rate for each interval, so that 
for each panel ID / time of measurement combination, I have a sales growth 
figure. So my desired output would look like this:

Panel ID (firm)        Time of measurement                      Sales   
Sales growth in percent
103                                3                        3.3million   .
103                                4                        6.0million   
81.81
103                                5                        8.2million   
36.66
103                                6                        8.9million   
8.53
104                                3                        45.2million   
.
104                                4                        46.5million   
2.87
104                                5                        43.2million  
-7.09
104                                6                        37.2million  
-13.88

Unfortunately, I keep running against a wall here. Do you have any 
suggestions as to how one could manipulate the data to arrive
at this sales growth variable?

Best regards,
Marcus
___________________________________
Dr. oec. Marcus Matthias Keupp, Dipl.-Kfm.
Head of Research Lab
University of St. Gallen
Institute of Technology Management
Dufourstrasse 40a
CH-9000 St. Gallen / Switzerland
Tel. +41 (0)71 224 7236
Fax +41 (0)71 224 7301
http://www.alexandria.unisg.ch/publications/Marcus_Keupp
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