STAT 6020 Introduction to Biostatistics Fall 2005 Dr. G. H. Rowell

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STAT 6020 Introduction to Biostatistics Fall 2005 Dr. G. H. Rowell

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STAT 6020 Introduction to Biostatistics Fall 2005 Dr. G. H. Rowell

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STAT 6020Introduction to BiostatisticsFall 2005Dr. G. H. Rowell

Class 3

Students in the class will take turns defining the terms listed in this presentation that they have listed in their homework.

Examples are helpful if you have them included, please mention them.

REVIEW

REVIEW

REVIEW

- Observational Study vs. Experiment
- Prospective vs. Retrospective
- Longitudinal vs. Cross-sectional
- Control vs. Treatment

- Variation: control what you can, randomize what you cannot control
- Cautions:
- Samples need to represent the population
- In comparative studies, make groups similar with respect to known sources of variation

- The Content of an Experiment: 3 Decisions to Make

- Three SOURCES of Variability: One We Want and Two We Don’t Want

- Three KINDS of Variability: One We Want, One We Can Live With, and One That Threatens Disaster

REVIEW

- Replicated Measures
- Balanced Design
- Randomization
- Covariates
- Sample size

REVIEW

- Bias (Bias vs. Chance Error)
- Randomization
- Blinding
- Replications
- Sample selection
- Sample size

- See diagrams on Pages 83 – 85

- For Hand-in Homework: Name: Randomization SimulationDue Date: Monday, Sept. 19 at 9:30 AM CSTPossible Points: 20Complete the Randomization Simulation Activity found athttp://mtsu.edu/~smcdanie/I_cubed/Lesson2/lesson2-Home.htm Be sure to submit the "pretest" and the "lesson" and the "feedback" forms. Note, there is a not a review for this lesson. Do NOT skip the "tutorial."

- HOMEWORK: AFTER you complete the randomization simulation, read Sect. 5.7 & define
- Simple Randomization
- Block (Restricted) Randomization
- Stratified Randomization
- Cluster Randomization

- Note: Skip Section 5.8 for now.

- Two Main Types of Observational Study used to investigate Causal Factors
- Case-Control (retrospective)
- Cohort (prospective)

- Big Picture
- Identify group with condition (case)
- Identify group without condition (control)
- Compare past exposure to factor for the two groups

- Advantage: relatively simple, quick, inexpensive, valuable with rare conditions
- Disadvantage: biases can occur
- Homework: Read 5.10.1 – 5.10.6

- Big Picture: follow-up study
- Identify group of subjects of interest
- Follow them to see what happens (Begin with unaffected observations & wait to see what happens)

- Advantage: careful measurement
- Disadvantage: could take a long time for a large enough proportion to be affected (expensive), not good for rare conditions
- Homework: Read 5.11

- All information is collected at the same time (subjects contact once)
- Descriptive Ex: Surveys
- Investigation of Associations – an alternative to the case-control and cohort approach

- Advantage: no recall bias, no loss to follow-up, cheap
- Disadvantage: Cannot draw clear inference of causality
- Homework: Read 5.12.

- Read Section 5.13 & 14
- Work Homework Problems # 1 -3.
- Check answers in the back of the book.