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From |
"RECAI AYDIN" <RECAI.AYDIN@lamar.edu> |

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

Subject |
st: RE: RE: R: Moran I and spatial correleation help needed |

Date |
Wed, 13 Feb 2008 12:32:13 -0600 |

I have read the article by Pisati but no additional help sine I already have been his modules. I still have same questions in my mind. That article only explains the mechanics of the commands I am using. I still need help for questions 1, 3 and 4 as Nick has already answered number 2. Thanks again. -----Original Message----- From: owner-statalist@hsphsun2.harvard.edu [mailto:owner-statalist@hsphsun2.harvard.edu] On Behalf Of Nick Cox Sent: Wednesday, February 13, 2008 11:57 AM To: statalist@hsphsun2.harvard.edu Subject: st: RE: R: Moran I and spatial correleation help needed Let me join these two postings: 1. This is precisely the set of programs that Recai Aydin is asking about. (Recai should have indicated where the programs come from.) 2. Carlo's helpful reference points up the general fact, just made public, that old issues of the STB are now accessible to all with internet access. 3. Thus Recai should read Maurizio's article within STB-61 if (s)he has not already done so. Just to pick up one of Recai's several questions: You are at perfect liberty to calculate Moran's I for some transformation of one of your variables, and for any nonlinear transformation the results will differ. The issues arising seem exactly like those with any transformed scale or link function: what is a suitable scale for analysis will depend on your problem, your data, and your intended analysis. Nick n.j.cox@durham.ac.uk Carlo Lazzaro Maurizio Pisati has suite of commands for spatial data analysis that may be useful. See http://www.stata-press.com/journals/stbcontents/stb60.pdf RECAI AYDIN I am new in "spatial correlation" and need your help. I appreciate if you can help me. here are the commands I run and I have no problem getting the output. However, I cannot say it for the output:) spatcorr value, bands(0 1.5 3 4.5) xcoord(x) ycoord(y)cumulative spatwmat, name(W) standardize xcoord(x) ycoord(y) band(0 1.5)eigenval(E) spatreg value sf sf2 age lot br fb pool d1 d2 d3 d4 d5, weights(W) eigenval(E) model(lag) spatreg lnvalue sf sf2 age lot br fb pool d1 d2 d3 d4 d5, weights(W) eigenval(E) model(error) My questions are: 1) I noticed that I can use only one variable after "spatcorr" and I assume it must be the dependent variable but that means the program is only checking for the spatial correlation in that variable alone without knowing what my full model is. That does not make sense to me. Then how does it determine if the spatial correlation is "lag" type or "error" type unless it defines the error as the deviation in Y? 2) I tried to run "spatcorr" with "lnvalue" as I normally use semi-log form and I got different Moran I. Can I use this command with transformed variable. How does that affect the interpretation of the I? 3) Is there any easy way of understanding if the spatial autocorrelation is due to "lag" or "error" from the output? 4) When I have the output for the last two lines (spatreg) and compare them with OLS, I do not see much difference even though Moran I, rho and lambda all are significant. How can I knoe that actually one is superior to the others. This last one is especially important for me. Because I really doubt about the importance of spatial autocorrelation and I need to be convinced by one of the "believers":). * * 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/ * * 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: Moran I and spatial correleation help needed***From:*"RECAI AYDIN" <RECAI.AYDIN@lamar.edu>

**st: R: Moran I and spatial correleation help needed***From:*"Carlo Lazzaro" <carlo.lazzaro@tin.it>

**st: RE: R: Moran I and spatial correleation help needed***From:*"Nick Cox" <n.j.cox@durham.ac.uk>

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