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

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

Subject |
RE: st: How to implement Wald estimator (for IV that is a ratio of coefficients)? |

Date |
Mon, 12 Oct 2009 13:10:32 +0100 |

Martin is clearly right to emphasise that local macros are local (to the program, do-file, do-file editor contents or interactive session in which they are defined) but I don't know any reason at all why local macros should die at the end of a line. Nick n.j.cox@durham.ac.uk Martin Weiss -local-s are what you would guess from their very name: local. I.e., they are local to your Stata session, or to a do-file you execute. If you do this line-by-line, they die at the end of the line. So you have to use -global-s or execute the whole thing. -local-s also do not take data type assignments such as "double". You can say ************* local double a 1 ************* but then you have created a -local- with name "double" that contains the string "a 1": Not at all what you wanted. Type "ma di" to see all -macro-s at any time... As you would guess, there is an article by Nick on the subject, but the SJ archive does not answer my calls today. I always get " Query failed: Incorrect information in file: './statajournal/main.frm'"... Misha Spisok Thank you, Professor Nichols--this answers a question I didn't ask but was at the back of my mind. The formula I noted neglected any possible covariance--is this the problem that arises in the context of using two separate estimations on a single dataset? I have two follow-up questions, one statistics-related and one Stata-related. 1. If I follow the -suest- in your example with the following: . nlcom [r1_mean]_b[nearc4]/[r2_mean]_b[nearc4] Does this give me the "correct" standard error? If so, is the difference (0.00001913) due to rounding? I attempted to use doubles in the code you provided, e.g., local double b1=_b[nearc4], but then I can't even find a workaround to the problem in my second question. When I get to . di `b1'/`b2'*sqrt((`s2'/`b2')^2+(`s1'/`b1')^2-2*`c'/`b1'/`b2') I get the error, 1572375310669762 invalid name 2. When I "do" (i.e., highlight a line of the do-file and hit the "do selected lines" button) each line of code from a do-file editor, then when I get to di `b1'/`b2' I get the error invalid syntax I (obviously to you probably, but not to me) don't have this problem if I either (i) do the entire do-file at once or (ii) enter contents interactively, line-by-line. I do, however, have a similar problem, as mentioned in my first question, if I change the local assignment to a "local double" assignment. I apologize for any imprecision or incorrect use in my terminology about locals, doubles, etc. * * 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/

**Follow-Ups**:**AW: st: How to implement Wald estimator (for IV that is a ratio of coefficients)?***From:*"Martin Weiss" <martin.weiss1@gmx.de>

**References**:**st: How to implement Wald estimator (for IV that is a ratio of coefficients)?***From:*Misha Spisok <misha.spisok@gmail.com>

**Re: st: How to implement Wald estimator (for IV that is a ratio of coefficients)?***From:*Stas Kolenikov <skolenik@gmail.com>

**Re: st: How to implement Wald estimator (for IV that is a ratio of coefficients)?***From:*Misha Spisok <misha.spisok@gmail.com>

**Re: st: How to implement Wald estimator (for IV that is a ratio of coefficients)?***From:*Austin Nichols <austinnichols@gmail.com>

**Re: st: How to implement Wald estimator (for IV that is a ratio of coefficients)?***From:*Misha Spisok <misha.spisok@gmail.com>

**AW: st: How to implement Wald estimator (for IV that is a ratio of coefficients)?***From:*"Martin Weiss" <martin.weiss1@gmx.de>

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