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Trajectories of Smoking Among College Freshmen: Data from the UpTERN Study

Trajectories of Smoking Among College Freshmen: Data from the UpTERN Study. Brian R. Flay, Eisuke Segawa, Donald Hedeker, Craig Colder and TERN members. Selection of Subjects for These Analyses. Fitted Curve for Standard Mixed Effect Model. Statistical Model: Hybrid of HLM & GMM.

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Trajectories of Smoking Among College Freshmen: Data from the UpTERN Study

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  1. Trajectories of Smoking Among College Freshmen: Data from the UpTERN Study Brian R. Flay, Eisuke Segawa, Donald Hedeker, Craig Colder and TERN members SPR, Washington DC, May 26 2005

  2. Selection of Subjects for These Analyses SPR, Washington DC, May 26 2005

  3. Fitted Curve for Standard Mixed Effect Model SPR, Washington DC, May 26 2005

  4. Statistical Model: Hybrid of HLM & GMM • In pure GMM, classification is dominated by intercepts • Our interest was more in changes over time, or slopes • Therefore, we specified a common (random-effect) intercept model • Model estimates only one intercept (mean over all subjects), but it provides intercept estimates for each subject as in HLM SPR, Washington DC, May 26 2005

  5. SPR, Washington DC, May 26 2005

  6. 7-class Common Random Intercept GMM SPR, Washington DC, May 26 2005

  7. Class 1: Increasers SPR, Washington DC, May 26 2005

  8. Class 2: Low-level increasers SPR, Washington DC, May 26 2005

  9. Class 3: Occasional Smokers SPR, Washington DC, May 26 2005

  10. Class 4: Regular Chippers SPR, Washington DC, May 26 2005

  11. Class 5: Reducing Chippers SPR, Washington DC, May 26 2005

  12. Class 6: Higher reducing chippers SPR, Washington DC, May 26 2005

  13. Class 7: High variation decreasers SPR, Washington DC, May 26 2005

  14. Classification by increase or decrease in smoking during the year SPR, Washington DC, May 26 2005

  15. What happened to these groups the following year? SPR, Washington DC, May 26 2005

  16. What happened to these groups the following year? SPR, Washington DC, May 26 2005

  17. Conclusions • The overall levels of smoking among college students are lower than expected • Nevertheless, some students increased their rates of smoking and others decreased • Hybrid HLM and Growth Mixture Analysis provided a meaningful grouping of students that described their patterns of smoking during freshman year • All smokers are at risk of increasing or maintaining their smoking levels! SPR, Washington DC, May 26 2005

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