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# More advanced techniques - PowerPoint PPT Presentation

More advanced techniques. &amp; A quick look at POLS 603. Simultaneous Equations. There are times when we are unsure of causation Consider the following hypotheses Presidents use military force intentionally to boost their popularity

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Presentation Transcript

&

A quick look at POLS 603

Simultaneous Equations
• There are times when we are unsure of causation
• Consider the following hypotheses
• Presidents use military force intentionally to boost their popularity
• When popularity is high, presidents are les restrained in their decisions to use force
• Does use of force cause changes in popularity, or do changes in popularity cause presidents to elect the use of force?
A Model of Presidential Popularity
• So:
• Note that since Use of Force is related to ut, and Popularity is related to et, there are correlated errors.
• We sometimes refer to this as an endogeneity problem.
Variable types
• This leads us to classify the variables in a model as one of three types:
• Endogenous variables – those that are determined within the model structure. The dependent variable is endogenous.
• Exogenous variables – those that are determined outside the model. The independent variables are exogenous.
• Lagged endogenous variables, which are often treated as exogenous variables due to their prior causation.
Simultaneous Causation
• Because of our prior hypotheses, we can infer that Presidential Popularity and the decision to use Military Force cause each other.
• They are simultaneously determined.
• For a sociologist, this is a non-recursive model.
Conditions to estimate Simultaneous models
• In order to estimate such a model, we have to satisfy certain conditions, which we call Identification:
• Order Condition: In order for an equation to be identified, it must exclude at least M-1 variables.
• Just Identified
• Over identified
• Rank Condition: An equation is identified if and only if at least one non-zero determinant of order (M-1)(M-1) can be constructed from the coefficients of the variables excluded from that equation.
Methods of estimation
• 2 Stage Least Squares (2SLS)
• 3SLS
• FIML
Uses
• Macroeconomic models of the economy.
• Sometimes, thousands of equations.
POLS 603
• Easier course than 602
• Readings harder in that they are more complex models, with more complex math
• Expectations about math are less
• Requirements
• Take home final with general comp style questions
• Paper using 1 advanced method
Topics for 603
• Matrix Algebra
• Time Series
• Univariate
• Multivariate
• Polled Cross sectional time series
• Vector Autoregression
• Others

Event History analysis

• Duration
• Survival
• Count Models
• Social Network Analysis
• Bootstrapping
• Computational Models (AI)