# PPPM 413 Study Guide - Final Guide: Dependent And Independent Variables, Statistical Parameter, Stata

by OC2231290

School

University of OregonDepartment

Planning, Public Policy and ManagementCourse Code

PPPM 413Professor

Grant JacobsenStudy Guide

FinalThis

**preview**shows half of the first page. to view the full**2 pages of the document.**PPPM 413 Finl Notes

Multivariate Regression

• Regression with 1+ independent variable

• ☺ ease with which it takes control variables into account

o Control variables helps examine if an observed relationship is a casual relationship

• A type of ordinary least squares regression

• Goal: Full Model Specification

o Accounting for all variables that affect a dependent variable

Model Specification

• The choice of variables included in the regression

• Eliminate bias in coef. of choice

o Difference between the expected estimated coef. (the value of b if there is an infinite

amount of data) and the true/casual value of parameter

o Omitted Variable Bias

▪ Most common type of bias

▪ Due to the omission of another relevant variable

▪ Only exists if the omitted variable (W) is correlated with BOTH X and Y

▪ Example:

• X <-> W -> Y

• If regress X -> Y ut don’t ontrol for W, then the oeffiient on X is

biased

o Bias phrasing:

▪ Absolute values:

• Overestimate: exp. value of coef. > true parameter in abs. value

• Underestimate: exp. value of coef. < true parameter in abs. value

▪ Actual values:

• Positively-biased: exp. value of coef. > true parameter (both +/-)

o X <–(+/-)–> W <–(+/-)–> Y

• Negatively-biased: exp. value of coef. < true parameter (mix of +/-)

o X <–(-/+)–> W <–(+/-)–> Y

• Equation:

o

o Dependent variable = independent variables (most important and other included

factors) + variables not in model (all excluded factors, residual)

Interpretation of individual coefficients (coef.)

• The coef. indicates the change in the DV associated with 1 unit change in the IV, holding

constant all of the other IV included in the regression

o Estimates can be made as though other IV do not change when the IV of interest

changes

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