Lecture slides stats1.13.l01.air
- 1. Statistics One Lecture 1 Experimental Research 1
- 2. Three Segments • Example 1: Polio Vaccine • Example 2: Memory Training • The concept of random 2
- 3. Lecture 1 ~ Segment 1 Example 1: Polio Vaccine 3
- 4. Polio Vaccine • In the first half of the century there were approximately 20,000 cases of polio per year in the USA • In 1952, there were 58,000 cases th 20 4
- 5. Polio Vaccine • In 1952, the first effective polio vaccine was developed by Dr. Jonas Salk – How do we know that it was effective? • Experimental research! • Randomized Controlled Experiments 5
- 6. Polio Vaccine • Sample – Initial • 4,000 children from Virginia – Final • 1.8 million children from 44 states • Population – All children in the USA 6
- 7. Polio Vaccine • Independent variable – Treatment • Vaccine • Placebo • Dependent variable – Polio diagnosis (measure of an individual child) – Rate of polio (measure of a group of children) 7
- 8. Polio Vaccine • Double-blind experiment – Experimenter did not know if the treatment was vaccine or placebo – Child (and parents) did not know if the treatment was vaccine or placebo 8
- 9. Polio Vaccine • Results – Rate (per 100,000) • Treatment: 28 • Control: 71 9
- 10. Polio Vaccine • By 1994 polio had been completely eradicated from all the Americas 10
- 11. Segment Summary • The major benefit of randomized experiments is they allow for strong claims about causality – Why stuff happens! • Predict stuff • Prevent bad stuff • Promote good stuff 11
- 12. Segment Summary • Strong causal claims require: – True independent variables – Random and representative samples – No confounds (impossible, but we try our best) 12
- 13. END SEGMENT 13
- 14. Lecture 1 ~ Segment 2 Example 2: Memory Training 14
- 15. Memory Training • Is it possible for adults to enhance their intelligence by training their working memory? – Promote good stuff! 15
- 16. Memory Training • Sample – College students • Population – Healthy adults 16
- 17. Memory Training • Independent variable – Training • Memory training • No training • Dependent variable – Gain in score on an intelligence test • IQ gain 17
- 18. Memory Training • Procedure – Treatment group engaged in memory training for a half hour every day for weeks • See next slide – IQ • All subjects completed a test of intelligence before and after training 18
- 22. Memory Training • Does it really work? – Potential confounds? 22
- 23. Segment Summary • The major benefit of randomized experiments is they allow for strong claims about causality – Why stuff happens! • Predict stuff • Prevent bad stuff • Promote good stuff 23
- 24. Segment Summary • Strong causal claims require: – True independent variables – Random and representative samples – No confounds (impossible, but we try our best) 24
- 25. END SEGMENT 25
- 26. Lecture 1 ~ Segment 3 The concept of random 26
- 27. Random • Experimental research requires: – Random selection – Random assignment 27
- 28. Random • Random selection – Individuals included in a sample should be randomly selected from the population 28
- 29. Illustration 29
- 30. Random 30
- 31. Not random 31
- 32. Random • Random assignment – Individuals are randomly assigned to conditions 32
- 33. Random assignment Group 1 Group 2 33
- 34. Segment Summary • Experimental research requires: – Random selection – Random assignment 34
- 35. END SEGMENT 35
- 36. END LECTURE 1 36