經濟實證與預測二實習
Empirical Study & Forecasting (II) : Recitation
李維倫 台大經濟系
2016.4.8
Instrument Variables (IV)
經濟實證與預測二實習
Fertility & Labor Supply
How much does a woman’s labor supply fall when she has an additional child?
Variable Description
morekids =1 if mom had more than 2 children boy1st =1 if 1st child was a boy
boy2nd =1 if 2nd child was a boy
samesex =1 if 1st two children same sex agem1 age of mom at census
black =1 if mom is black hispan =1 if mom is Hispanic
othrace =1 if mom is not black, Hispanic or white
weeksm1 mom's weeks worked in 1979
Mothers' Weeks Worked in 1979
(1) (2) (3)
Variables OLS 2SLS 2SLS
morekids -5.387*** -6.314*** -5.821***
(0.0871) (1.275) (1.246)
agem1 0.832***
(0.0226)
black 11.62***
(0.232)
hispan 0.404
(0.261)
othrace 2.131***
(0.211) Constant 21.07*** 21.42*** -4.792***
(0.0561) (0.487) (0.390) Obs. 254,654 254,654 254,654 R-squared 0.014 0.014 0.044
OLS estimation
Endogeneity Problem
Samesex as an IV
Relevance Exogeneity
Is samesex a weak IV?
IV estimation (2SLS)
Stata Codes
ivregress 2sls weeksm1 (morekids = samesex), first r
_cons .3464248 .001341 258.34 0.000 .3437965 .3490531 samesex .0675253 .001919 35.19 0.000 .0637641 .0712865 morekids Coef. Std. Err. t P>|t| [95% Conf. Interval]
Robust
Root MSE = 0.4844 Adj R-squared = 0.0048 R-squared = 0.0048 Prob > F = 0.0000 F( 1, 254652) = 1238.17 Number of obs = 254654
First-stage regressions
Stata Codes
ivregress 2sls weeksm1 (morekids = samesex), first r
Instruments: samesex Instrumented: morekids
_cons 21.42109 .4872487 43.96 0.000 20.4661 22.37608 morekids -6.313685 1.274681 -4.95 0.000 -8.812013 -3.815357 weeksm1 Coef. Std. Err. z P>|z| [95% Conf. Interval]
Robust
Root MSE = 21.715
R-squared = 0.0139
Prob > chi2 = 0.0000
Wald chi2(1) = 24.53
Instrumental variables (2SLS) regression Number of obs = 254654
為何高學歷攤販的利潤較高？
主計總處：民國
102
年攤販經營概況調查 幾乎所有的攤販都是經營零售及餐飲業若將攤販從業員工計入零售及餐飲業的員工，攤販從 業員工占全體零售及餐飲業的比例約為三成
攤販從業員工人數中，業主及無酬家屬工作者占
