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From |
Nick Cox <njcoxstata@gmail.com> |

To |
statalist@hsphsun2.harvard.edu |

Subject |
Re: st: Re:Grouping data/Probability Transition Matrix |

Date |
Tue, 3 Apr 2012 09:08:07 +0100 |

I would call your new variable a 5-category nominal or categorical variable. It is not a dummy variable. I note that replace InitialSize=4 if emp>=250& & year==1991 is illegal. With the superfluous "&" removed it will include firms with missing -emp- in 1991. Also -InitialSize- of 0 includes all data for 1992-1999. That's what you asked for at the outset, and nothing changed it. I would not do your analysis your way as I dislike coarsening data, but that aside I would go gen Initial = 1 if emp<10 & year==1991 replace Initial = 2 if emp>=10 & emp<50 & year==1991 replace Initial = 3 if emp>=50 & emp<250 & year==1991 replace Initial = 4 if emp>=250& emp < . & year==1991 Then presumably there is an identifier with which you can go. bysort id (year) : replace Initial = Initial[1] Transitions are standard -xt- stuff. See help on -xttrans-. Nick On Tue, Apr 3, 2012 at 2:20 AM, tunmise jones <tunmisejones@gmail.com> wrote: > I am currently working with a balanced panel dataset of companies over a period > of 9 years (1991-1999) to track employment growth over the period. > > I would like to group firms into 4 size classes based on size > (employment) in 1991. Based on the size classes, I ran the following > commands: > > gen InitialSize=0 > Replace InitialSize=1 if emp<10& !mi(emp) & year==1991 > Replace InitialSize=2 if emp>=10& emp<50& year==1991 > Replace InitialSize=3 if emp>=50& emp<250 & year==1991 > Replace InitialSize=4 if emp>=250& & year==1991 > > and obtained a four category dummy variable. I tried to group the > entire dataset based on these categories and run separate regressions > for each size class. It would appear observations for the regressions > are only being limited to this sub-sample of firms in the first year. > > Following the above commands, > > 1. How can I classify all the firms into size classes based on their > initial size (1991 size)? > 2. Following from this, how can I estimate transition probability > matrix for 1991 and 1999 to track firm mobility across the 4 size > classes? * * 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: Re:Grouping data/Probability Transition Matrix***From:*tunmise jones <tunmisejones@gmail.com>

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