Course Overview: Applications

Overview

We have to review some core tools/ideas in statistics:

  • Basics of distributions, populations vs sample. Mean, variance, etc
  • Sample mean \(\rightarrow\) large sample theory \(\rightarrow\) population mean (estimation)
  • Hypothesis testing and confidence intervals
  • Linear models and linear regression

First, some research to motivate us.

Application 1: Credit Constraints and Human Capital

  • “The Nature of Credit Constraints and Human Capital”, Lochner and Monge-Naranjo, American Economic Review (2011)
  • Theory:
    • Incomplete markets can lead to underinvestment in human capital (agents cannot borrow against returns to investment).
    • Controlling for returns, income/wealth should not predict investment unless borrowing constraints bind.
  • Question: Evidence of credit constraints in college enrollment decisions?
  • Data NLSY79 and NLSY 97 (two cohorts of young individuals)
  • Key idea: How do skills (measured by AFQT) and parental income predict college enrollment?

Application 1: Credit Constraints and Human Capital

  • Consistent gradient in AFQT (cog skill)
  • Family income more important in 97 cohort
  • Suggestive evidence of more binding constraints
  • No testing here: how to test formally?

Application 2: Teacher Incentives in Rural India

  • Paper: “Incentives Work: Getting Teachers to Come to School”, Duflo, Hanna, and Ryan, American Economic Review (2012)
  • Background: expanding access to primary education crucial in developing countries. Teacher absenteeism in India is a big problem.
  • Theory: providing incentives should increase attendance.
  • The Paper: evaluates a teacher incentive program by RCT.
  • Data: Attendance and student outcomes for 57 treatment schools, 56 control schools run by Seva Mandir (NGO)

Application 2: Teacher Incentives in Rural India

Details on “treatment”:

  • Monitoring via tamper-proof cameras.
  • Financial incentives for teachers: \[ \text{Rupees per month} = 500 + 50\times\max\{0,D - 10\} \] where \(D\) is days attended per month.
  • Financial incentives or fear of punishment?
  • Notice: no incentive if: \[ \text{Days attended so far} + \text{Days left in month} \leq 10 \]

Application 2: Teacher Incentives in Rural India

  • Visual evidence of effect.
  • But how to estimate size of effect?
  • Quantify uncertainty?
  • No testing here: how to test formally?
  • Can do a regression analysis…

Application 2: Teacher Incentives in Rural India

  • How to interpret this table?
  • How are standard errors calculated? \(R^2\)?
  • Fixed Effects? Clustering?
  • Will learn how to replicate and interpret this graph.