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

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

Subject |
st: RE: deming regression |

Date |
Thu, 28 Feb 2008 13:40:08 -0000 |

-deming- is an unofficial command written by Yulia Marchenko (who just happens to work for StataCorp). It expects to be fed the coefficients of variation, or strictly 100 times those. Recall that coefficient of variation is standard deviation/mean. The method you refer to requires quite different input and on the face of it is different. However I think it would need someone to read that paper and also look inside Yulia's program to see whether they are or are not equivalent. My experience in this territory is that there are many different procedures all aimed at situations in which both variables are measured with error. What you do has to be based on what you can assume about the underlying situation. The literature is also scattered across disciplines and full of papers claiming that they know the best procedure and that others are wrong or not nearly so good. The same procedure also often appears under quite different names in various places. Recently I came across a reference to "neutral regression" for example, which sounds a good term, except that I still seek a precise definition. See also -concord- (-findit concord-) which includes a reduced major axis (SD line) option and includes various little tools for method comparison. Nick n.j.cox@durham.ac.uk Subramanian Swaminathan I have a problem in giving inputs to the 'deming' command in stata. From a paper by "Cornbleet, PJ and Gochman, N (1979). Incorrect least squares regression coefficients in method-comparison analysis, Clinical Chemistry 25, 432-438", I understand that they used a parameter called 'lambda', which is the ratio of the within-individual variance of the indepdent variable and the within-individual variance of the dependent variable. This parameter can be estimated from repeated measurements of depdent and indepdent variables. My question is, do the the values of cv1 and cv2 in stata are based on the values of var1 and var2? if so, how is it related to the 'lambda' parameter of the above stated paper? If such repeat measurements not available, what value should be used for inputting to cv1 and cv2? * * 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/

**References**:**st: deming regression***From:*Subramanian Swaminathan <ssubra@yahoo.com>

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