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Published byElvin Oliver Modified over 8 years ago
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Nonrandom Sampling and Tobit Models ECON 721
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Different Types of Sampling Random sampling Censored sampling Truncated sampling Nonrandom –Exogenous stratified –Endogenous stratified Choice-based
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Tobit Models Main reference: Amemiya, Chapter 10
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Type I Tobit Model Tobin’s (1958) example – expenditure on a durable good only observed if expenditure exceeds the minimum price available.
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Truncated Type I Tobit Only observe data for people who purchased the good (e.g. gather data at appliance store)
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Ways of Estimating Tobit Model MLE If censored, estimating probit and get coefficients up to scale By OLS using results for conditional means of truncated normal random variables
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Heckman’s Two-Step Procedure
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NLLS
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Tobit Type III Model
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likelihood
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Estimation by MLE
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Example: Gronau’s female labor supply model
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Heckman’s female labor supply model (explains choice of H as well)
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Type III Tobit Model (observe both wages and hours)
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Estimation MLE Two-step method
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Type V Tobit Model
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