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 Biostatistics 140.653
 Methods in Biostatistics III

  Department of Biostatistics, Johns Hopkins Bloomberg School of Public Health

 

Date

Class  

Work
Due
Lecture Topic Reading  
Assignment

Tues
Jan 22
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1  

Introduction/overview

  • Statistical modeling

  • Regression and correlation
  • Parameter interpretation: slopes; means
  • Analytic purposes
FEH: Ch 1
SW: Ch. 1
Thurs
Jan 24
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2  

Model and estimation: Simple linear regression

  • Statement of model, assumptions

  • Estimation: Least Squares
  • "Quality" of estimation: Accuracy, precision
SW Ch. 2.1-2.4
Tues
Jan 29
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3  

Simple linear regression: Sample characteristics and random component estimation

  • Isolated points; influence ("sensitivity")

  • Decomposition of variance: ANOVA table

  • Residual variance estimation

  • Brief inference introduction

SW: 2.5-2.9
Thurs
Jan 31
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4

 Problem
Set 1 due
5 PM
FEB 1

Multiple linear regression: uses

  • Multiple predictors

  • Direct versus total effects
  • Nonlinear relationships: Polynomials/splines
  • Categorical predictors: Dummy variables
FEH: Ch 2
SW Ch. 6.1-2

 

Tues
Feb 5
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5

 

Model and estimation: Multiple linear regression 

  • Statement of model, assumptions

  • Matrix specification
  • Least squares in the multiple covariate setting
  • Gauss-Markov theorem
  • Introduction to inference: variance components
SW: 3.1-3.4
Thurs
Feb 7
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6  

Inference in multiple linear regression

  • t-based inference for individual parameters

  • Global/F-tests, regions for multiple parameters
  • Confidence intervals for contrasts, model
SW Ch. 3.5;
scan Ch. 4
Tues
Feb 12
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7  

More on models with multiple covariates

  • Adjustment

  • Effect modification / interaction

  • Mediation
  • Multiple comparisons
Revisit
FEH Ch. 2
Thurs
Feb 14 
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8 Problem
Set 2 due
5 PM
FEB 13
Case study / review  
Tues
Feb 19
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9   Midterm Examination  
Thurs
Feb 21 
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10

 

Model checking

  • Residual versus predicted plots

  • Standardized, studentized residuals
  • Partial residual plots
  • Outliers, influential points
SW Ch. 8-9
Tues
Feb 26
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11  

Model checking: Two-stage regression

  • Partial correlation / Adjusted variable plots

  • Inference in the face of assumption violations

    • Nonlinearity: transformations

    • Heteroscedasticity: transfrms, weighting

    • Correlation: robust variance

FEH Ch. 9;
SW Ch 3.1;
scan Chs 5
and 7
Thurs
Feb 28
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12 Problem
Set 3 due
5 PM
FEB 29

Prediction

  • Inference for fitted values; sums of coefficients

  • Colinearity

  • Multiple R-squared

  • Confidence bands / prediction intervals

SW Ch. 2.8.3;
10.1

Tues
Mar 4
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13

 

Prediction continued
  • Overfitting; cross-validation
  • Mallows’ CP (bias-variance tradeoff)
  • PRESS
FEH: Ch 5
Thurs
Mar 6
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14

 

Model building strategies
  • Parsimony
  • Role of theory; variable groupings
  • Data based methods: AIC, BIC
  • Automated methods
  • Extrapolation;
  • Propensity scoring
FEH Ch. 4;
SW Ch. 10.2-10.4
Tues
Mar 11
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15 Problem
Set 4 due
in class
Case study / review FEH: Ch 7
Thurs
Mar 13
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16

 

FINAL EXAMINATION  

  • FEH: Harrell, F.E. (2001), Regression Modeling Strategies, With Applications to Linear Models, Logistic Regression, and Survival Analysis, New York: Springer.

  • SW: Weisberg S. (2005), Applied Linear Regression, 3rd. Ed., New York: John Wiley & Sons


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 Last edited: 14 January, 2008

 

 ©2008, Department of Biostatistics,
            Johns Hopkins Bloomberg School of Public Health
            All Rights Reserved