M ODEL IS W RONG ?! S. Eguchi, ISM & GUAS
What is MODEL? No Model is True ! Feature of interests can reflect on Model Patterns of interests can incorporate into Model Observations can only be made to finite precision ● ● ● Cf. J K Lindsay “ Parametric Statistical Inference ”
Asymptotics on correct model Large sample asymptotics Asymptotic consistency, normality Asymptotic efficiency (Higher-order asymptotics) Non-parametric asymptotics
Outline ● Near-Model Bridge para and non-parametrics Non-efficiency under Near model ● ●
Near model parametric non-parametric near-parametric
Tubular Neighborhood M g
Density estimation Estimate g(y) Kernel estimate
Local Likelihood The main body Localization versions (Eguchi, Copas, 1998)
Local likelihood density estimate Maximum Local Likelihood Estimator The density estimator normalizing const )
h y
Global vs Local likelihood Global (h = ) Local (h = 3.65) opt
Regression function Estimate (x) = E(Y|x) GLM Cf.Eguchi,Kim,Park (2002)
Bridge of nonpara / parametric
Discriminant Analysis Input vectorlabel Logistic model Almost logistic model
A class of loss functions For a given data Estimate the score
Logistic loss
Error rate Medical screening where
Empirical loss For a training data score
Estimating function IRLS where Logistic
Asymptotic efficiency Cramer-Rao type ( logistic loss) .
Risk under correct model Under the correct model Expected D-loss Let
Risk under near model where Let
λ-family Target risk λ-family score
λ (Proof ) opt (Eguchi, Copas, 2002)
Some analysis False positive rate 0.435% 0.423% λ
Conclusions ● Near-Model Bridge para and non-parametrics Non-efficiency under Near model ● ● α-neighborhood
Future project??