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From |
tashi lama <ltashi32@hotmail.com> |

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

Subject |
RE: st: documentation on iteration for a non linear regression |

Date |
Wed, 13 Jun 2012 15:04:12 +0000 |

That would help. Thanx... but it doesn't hurt to learn more although I am planning to spend a day or two to go through the manual on matrix, sth I haven't looked at before. I had a dataset as follows day hits b v | |---------------------------------| 1. | 03jan2011 211 1 209.0752 | 2. | 04jan2011 60 2 69.08601 | 3. | 05jan2011 28 3 22.82851 | 4. | 06jan2011 16 4 7.543365 | ---------------------------------------- v is my predicted value. day and hits are my original value and I generated b to use it as independant variable instead of day for simplification. Drawing a scatter plot helped me identify the nature of the curve which is exponential so i decided to use one of the built in exp models. So, I said nl exp2 :hits b which returned e(b) among many things. if you don't remember exp2 is exp2: y = b1*b2^x. I was having difficulty accesssing my e(b) if I wanted to use it in my dofile. The manual suggests _b[varname] and _se[varname]. Also says... use _b[_cons] and _se[_cons] for constant. I was confused. Thanx.. > From: n.j.cox@durham.ac.uk > To: statalist@hsphsun2.harvard.edu > Date: Wed, 13 Jun 2012 15:50:53 +0100 > Subject: RE: st: documentation on iteration for a non linear regression > > It all depends on what command you are using. You don't say what command you used previously (another piece of advice being ignored), but after -nl- (for example) common steps would be > > mat b = e(b) > > di b[1,1] > > di b[1,2] > > scalar b1 = b[1,1] > > scalar b2 = b[1,2] > > Nick > n.j.cox@durham.ac.uk > > tashi lama > > Sorry, I read and reread the manual. I am confused. The manual says _b[varname] and _se[varname] to access the coeff and standard error of a var and _b[_cons] and _se[_cons] to access the coeff and standard error of a constant. I am fitting a exponential model y=b1*b2^x to my dataset and got e(b) as > > mat li e(b) > > e(b)[1,2] > b1: b2: > _cons _cons > y1 632.7252 .33046311 > > di _b[_cons] gave me the coeffiecient i.e. 632.73. In the same spirit, I would assume I do di _b[x] to get the coeff of x. There is an error which reads [x] not found. Any idea? > > * > * 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/

**Follow-Ups**:**Re: st: documentation on iteration for a non linear regression***From:*Austin Nichols <austinnichols@gmail.com>

**References**:**st: documentation on iteration for a non linear regression***From:*tashi lama <ltashi32@hotmail.com>

**Re: st: documentation on iteration for a non linear regression***From:*Nick Cox <njcoxstata@gmail.com>

**RE: st: documentation on iteration for a non linear regression***From:*tashi lama <ltashi32@hotmail.com>

**Re: st: documentation on iteration for a non linear regression***From:*William Buchanan <william@williambuchanan.net>

**RE: st: documentation on iteration for a non linear regression***From:*tashi lama <ltashi32@hotmail.com>

**Re: st: documentation on iteration for a non linear regression***From:*Phil Clayton <philclayton@internode.on.net>

**Re: st: documentation on iteration for a non linear regression***From:*Maarten Buis <maartenlbuis@gmail.com>

**RE: st: documentation on iteration for a non linear regression***From:*tashi lama <ltashi32@hotmail.com>

**RE: st: documentation on iteration for a non linear regression***From:*Nick Cox <n.j.cox@durham.ac.uk>

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