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From |
"Nick Cox" <n.j.cox@durham.ac.uk> |

To |
<statalist@hsphsun2.harvard.edu> |

Subject |
st: RE: Bracket [ ] notation |

Date |
Tue, 9 Aug 2005 22:09:20 +0100 |

If the subscript on the RHS is missing (meaning not present in the dataset), the result on the LHS will be missing too (meaning "missing"). Here the use of -by:- is just a detail and does not affect the principle. The principle can be seen by sysuse auto di mpg[0] di mpg[75] As advised in another thread, you would surely be better off re-casting this using time-series operators. Nick n.j.cox@durham.ac.uk P.S. the spelling is Stata. Terra Curtis > I am running into some problems trying to run a nonlinear > regression. I > continue to get error 480 "starting values invalid or some > RHS variables > have missing values." I think I see where my error is but > I'm not sure how > STATA deals with a reference, say 'by varname: data[x]' if x > is out of the > range of data for that varname. Here is my code: I have > written a program > to specify the nonlinear equation, and that is where the error is: > > program nlstk2_depreciation > version 8.1 > if "`1'" == "?" { > global S_1 "B3 B4 B5 drd2 dmktg2" > global B3=1 > global B4=1 > global B5=1 > global drd2=0.15 > global dmktg2=0.15 > exit > } > forvalues x=10/53 { > by coname: replace `1'=$B3+$B4*(ireal46[`x'] + > (1-$drd2)*ireal46[`x'-1] + (1-$drd2)^2*ireal46[`x'-2] + > (1-$drd2)^3*ireal46[`x'-3] + (1-$drd2)^4*ireal46[`x'-4] + > (1-$drd2)^5*ireal46[`x'-5] + (1-$drd2)^6*ireal46[`x'-6] + > (1-$drd2)^7*ireal46[`x'-7]+ (1-$drd2)^8*ireal46[`x'-8] + > (1-$drd2)^9*ireal46[`x'-9]/$drd2) + $B5*(imktg[`x'] + > (1-$dmktg2)*imktg[`x'-1] + (1-$dmktg2)^2*imktg[`x'-2] + > (1-$dmktg2)^3*imktg[`x'-3] + (1-$dmktg2)^4*imktg[`x'-4] + > (1-$dmktg2)^5*imktg[`x'-5] + (1-$dmktg2)^6*imktg[`x'-6] + > (1-$dmktg2)^7*imktg[`x'-7] + (1-$dmktg2)^8*imktg[`x'-8] + > (1-$dmktg2)^9*imktg[`x'-9]/$dmktg2) if `x'==year > } > end > > I have panel data for companies over a period of years, although each > company has a different amount of years of data (no company > has more than 53 > years of data). If a company has 10 years of data, I want > the regression to > use all 10 years of data. If it has more than 10 years of > data, I want it > to use the most recent 10 (say, years 1990-1999), then use the next 10 > (years 1989-1998), and so on until it gets to the last set of > 10 years for > that company. I think the logic of the equation I have > written works out, > so I'm guessing the error is coming from some referencing > problem in the > brackets...I don't quite understand how STATA would deal with > ireal46[49] if > some company didn't have a 49th ireal46 entry. > * * For searches and help try: * http://www.stata.com/support/faqs/res/findit.html * http://www.stata.com/support/statalist/faq * http://www.ats.ucla.edu/stat/stata/

**Follow-Ups**:**st: RE: RE: Bracket [ ] notation***From:*"Terra Curtis" <terra.curtis@cambridgefinance.com>

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