Trip Generation Modeling Linear Regression

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Trip Generation ModelingLinear Regression

• CE 573 Transportation Planning
• Lecture 5

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Objectives

• Regression review
• Trip generation and regression

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Linear Regression Review

• Raw data
• Dependent variable (Y)
• Independent variable (X)
• Generic model?

4
Linear Regression Review

• Calibrating the model
• Solving for b
• Deviation in X?
• Equation 4.6 for b?

5
Linear Regression Review

• Calibrating the model
• Solving for a
• Average deviation in zero intercept model
  Equation 4.5 corrected

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Linear Regression Review

• Variance of the estimators

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Linear Regression Review

• Hypothesis tests for b
• Ho b 0 H1 b ? 0
• Ho rejected if 0 is not with in an appropriate
  confidence interval of the estimated parameter
• test statistic Equation 4.8 and variance of the
  model residuals

8
Linear Regression Review

• Hypothesis testing
• t vs tcritical http//en.wikipedia.org/wiki/Stude
  nt27s_t-distribution
• See t-distribution table

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Multiple Regression

• Multicollinearity Independent variables
  linearly related
• Number of independent variables??
• include if
• strong theoretical backing
• needed for policy decisions
• Coefficient of determination (R2)
• inflates with each addition of an independent
  variable

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Trip Generation Modeling Using Regression

• Aggregate (zonal)?
• Disaggregate (household) ?
• Zonal based multiple regression
• Sample units?
• Independent variables ?
• Define the variables in terms of ___________
• Household based regression
• Sample units ?

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Regression and Non-Linearity

• Variable transformation
• Y x2 relationship

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Regression and Non-Linearity

• Dummy variables
• 0 car model ?aX
• 1 car model ?bX
• 2 car model ?cX