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MBA (IT), PHD
Kaplan University
Apr-2009 - Mar-2014
Professor
University of Santo Tomas
Aug-2006 - Present
It is quantitative
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Ordinary least squares is a technique for estimating unknown parameters in a linear regression model. OLS yield the maximum likelihood in a vector β
, assuming the parameters have equal variance and are uncorrelated, in a noise ε - homoscedastic.
Â
y→=Xβ→+ε→
Â
Generalized least squares allows this approach to be generalized to give the maximum likelihood estimate β
when the noise is of unequal variance (heteroscedasticity). Typically this leads to mathematical treatment that presents the two as follows: OLS: Y→=Xβ+ε where ε~N(0,σ²I) GLS: Y→=Xβ+η where η~N(0,σ²Cov) Note the formulation for the two approaches results in real structural and quantitative difference. Notice the two are governed by two different Gauss distribution the N(0,σ2M);M=I or M=Cov part Where: I= "Identity Matrix and " Cov=
"Covariance Matrix
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