LDA - Bio 655 LABS

140.655.01 - Third Term 2008 LONGITUDINAL DATA ANALYSIS Johns Hopkins Bloomberg School of Public Health

LABS

WARNING: The lab materials are posted before the day of the lab to allow you to prepare in advance of the lab. Be aware that the materials will often be slightly modified the evening before the lab. If you plan to print the materials and want to ensure that you have the most recent version, print the lab document the morning of the lab.
HELPFUL HINT: Download each of the STATA *.ado files and the corresponding *.hlp file. Use "Save As Source" when you save them to your hard disk from your web browser. To use the *.ado files, put them in your current directory, in your STATA "ado" directory, or in a directory where STATA will know where to look for them.

► LAB 1 (Monday 1/28/08) : Introduction to STATA for longitudinal data analysis

STATA Intro for LDA (.pdf)

Additional Material:

Supplementary material for lab 1 [Basic STATA Intro (.pdf)] lab1.log lab1.do

Faster function to generate smooth model fits [ksmapprox.ado][ksmapprox.hlp]
Function for making plots of means over time [xtgraph.ado] [xtgraph.hlp] pdf demonstration file
Function to compute sample autocorrelation function for fixed time points of equal lag [autocor.ado] pdf help file
variogram: Variogram plot [variogram.ado] [variogram.hlp] This function requires [xtdiff.ado] and [ksmapprox.ado]
Introductions to SAS [sas_intro.pdf] [sas_intro2.pdf]
Glossary of Macros [sascode.pdf]
Also, please check the corresponding SAS functions and analysis in the Software section of the website.

►LAB 2 (Wednesday 1/30/08) : Matrix Review & Finish Lab 1 [Matrix Review.pdf]

►LAB 3 (Monday 2/4/08) : Exploratory Data Analysis for mean function

Exploring the mean function in the pigs data (to be done in lab) [Lab3_EDAmean.pdf] [Lab3_EDAmean.do]
Exploring the mean function in the dental data set (extra practice with solutions) [Lab3_EDApractice.pdf]

►LAB 4 (Wednesday 2/6/08) : Exploratory Data Analysis for Correlation Structure

Exploratory Data Analysis for Correlation Structure [Lab4_EDAcorr.pdf] [Lab4_EDAcorr.do]
Please also refer to Lab1 to download associated ado files: variogram.ado ; autocor.ado; ksmapprox.ado and xtdiff.ado.

►LAB 5 (Monday 02/11/08) : Linear regression with within-subject correlation

Linear regression with within-subject correlation [Lab5_LinearReg.pdf] [Lab5_LinearReg.do] , exercise using dental data set [Lab5_LinearRegPractice.doc]

►LAB 6 (Wednesday 2/13/08) : Review Homework 1 Solutions

►LAB 7 (Monday 02/18/08) : Review and robust estimation of standard error

Choosing a covariance structure and robust estimation of standard errors [Lab7_Sitka.Cov.Struct.pdf] [Lab7_Sitka.Cov.Struct.do]

►LAB 8 (Wednesday 2/20/08) : Q&A for Midterm

►LAB 9 (Monday 02/25/08) : Last Minute Q&A for Midterm

►LAB 10 (Wednesday 2/27/08) : Logistic regression analysis with Nepal Breastfeeding data

Marginal (GEE) models (New! 2/27/08 11am) Updated to include agec instead of age in models - results do not change (only the estimated intercepts in the models change) [Lab10_binary.nepal.pdf] [Lab10_binary.nepal.do]

►LAB 11 (Monday 03/3/08) : Logistic regression analysis with Nepal Breastfeeding data, Part II

Random intercept (Subject specific) models and transition models [Lab11_binary.nepal.pdf] [Lab11_binary.nepal.do]

►LAB 12 (Wednesday 3/5/08) : Review Homework 2 Solutions

►LAB 13 (Monday 3/10/08) : Q&A for Final

►LAB 14 (Wednesday 3/12/08) : Last Minute Q&A for Final