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From |
Charles Koss <hqtiger@gmail.com> |

To |
statalist@hsphsun2.harvard.edu |

Subject |
Re: st: calculate concentration ratio of four firms |

Date |
Mon, 28 Dec 2009 12:25:09 -0600 |

I use sas for data management, it is easier! In stata search for the egen function -- Charles Koss http://charlesonnet.blogspot.com/ 2009/12/27 Alper [iso-8859-9] Sönmez <salper@metu.edu.tr>: > Hi, I want to calculate the first four firms share in each industry at > time t (HHI4 or CH4). I calculated the shares but i cannot sum first four > firms shares in each industry at time t. > I tried egen and gen commands with several functions but they were not > worked > Also i did not find any solution or material from stata books and online > resources > I have an Unbalanced firm level panel data with variables id, years(t) > 2003-2006, and 2digitsectors(Sector)and it is in long form > > The problem: > I calculated > 1stly, total sales of industry j at time t (Yjt) > 2ndly, share of a firm i in industry j (sales of firm i/Yjt)*100=a > 3rd a^2 for each firm at time t > > 4 step is problematic: I can not calculate shares of first four firms in > sector j at time t > like this max(a+a+a+a) by (sector year) and write this value for firms in > these sector and year > > Please help me, > > in advance thanks, > > > > > > -- > Alper Sönmez > > ODTÜ/METU > ÝÝBF Ýktisat Bölümü/FEAS Department of Economics > Ankara Türkiye > Tel/Phone:0312 210 30 77 > Fax: 0312 210 79 64 > > > > > * > * For searches and help try: > * http://www.stata.com/help.cgi?search > * http://www.stata.com/support/statalist/faq > * http://www.ats.ucla.edu/stat/stata/ > * * For searches and help try: * http://www.stata.com/help.cgi?search * http://www.stata.com/support/statalist/faq * http://www.ats.ucla.edu/stat/stata/

**References**:**st: calculate concentration ratio of four firms***From:*"Alper [iso-8859-9] Sönmez" <salper@metu.edu.tr>

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