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From |
"Hong, Sounman" <sounman_hong@hksphd.harvard.edu> |

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

Subject |
st: confirmatory factor analysis using gllam in stata |

Date |
Sun, 16 Jan 2011 22:10:59 -0500 |

My question build upon a previous Q&A. I found a question that is fundamentally the same as mine. But I cannot understand the posted answer. Let's first look at the question and answer. This is the question. > Hi all, > I have a scale composed of 15 variables (items in a 5-point likert scale) that correspond to 3 factors/domains. How do I run CFA using gllamm. > My data: > Suppose the variable names are x1-x15 and the factors are f1 f2 and f3. > f1 corresponds to variables x1-x5 > f2 corresponds to variables x6-x10 > f2 corresponds to variables x11-x15 > I tried using the eq syntax to define the factors (equations) using the following syntax: > eq f1: x1-x5 > eq f2: x6-x10 > eq f3: x11-x15 > but where do I go from here? I'll not even post all my attempts. > Any ideas? =============================== This is the answer posted for the question If that's a linear model, then first you need to -reshape- your data so that each variable is now an observation within a block corresponding to one unit: g long ID = _n reshape long x, i(ID) Then you need to link your factors to your variables (which are now observations): bysort ID: g byte d1 = _n<6 by ID: g byte d2 = (_n>5) & (_n<11) by ID: g byte d3 = _n > 10 g byte ones = 1 Now define your equations: eq 101 : ones d1 d2 d3 eq 102 : ones d1 d2 d3 eq 103 : ones d1 d2 d3 Now you are ready to run -gllamm-: gllamm x, i(id) eqs(101 102 103) nrf(3) ============================= So, my question is that I don't understand the "eq" commands in the answer above. It seems like the answer defines three equations with 3 factor variables and the variable "ones". But why? I was thinking the following. eq factor1 : d1 eq factor2 : d2 eq factor 3: d3 gllamm x, i(id) eqs(d1 d2 d3) nrf(3) Is there anything wrong with my stata codes?? What is the difference between my command and the answer posted above? How should I change it? Any idea? Any reply would be greatly appreciated. * * 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: confirmatory factor analysis using gllam in stata***From:*Stas Kolenikov <skolenik@gmail.com>

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