Lecture Slides Stats1.13.L02.AIR

5/27/2018 Lecture Slides Stats1.13.L02.AIR

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Statistics One

2


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1:

2:

3:


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2~ 1

1:


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, 1 , ,

. , . Steven Pinker


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Polio Vaccine

In 1952, the first effective polio vaccin

developed by Dr. Jonas Salk How do we know that it was effective?

Experimental research! Randomized Controlled Experiments


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Polio Vaccine

Sample Initial

4,000 children from Virginia Final

1.8 million children from 44 states

Population All children in the USA


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Polio Vaccine

Independent variable Treatment

Vaccine Placebo

Dependent variable Polio diagnosis (measure of an individua Rate of polio (measure of a group of chil


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Polio Vaccine

Double-blind experiment Experimenter did not know if the treatm

vaccine or placebo

Child (and parents) did not know if thetreatment was vaccine or placebo


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Polio Vaccine

Results Rate (per 100,000)

Treatment: 28 Control: 71


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Polio Vaccine

By 1994 polio had been completelyeradicated from all the Americas


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Segment Summary

The major benefit of randomizedexperiments is they allow for strong c

about causalityWhy stuff happens!

Predict stuff Prevent bad stuff Promote good stuff


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Segment Summary

Strong causal claims require: True independent variables Random and representative samples

No confounds (impossible, but we try ou


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END SEGMENT


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Lecture 1 ~ Segment 2

Example 2: Memory Training


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Memory Training

Is it possible for adults to enhance thintelligence by training their working

memory? Promote good stuff!


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Memory Training

Sample College students

Population Healthy adults


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Memory Training

Independent variable Training

Memory training No training

Dependent variable Gain in score on an intelligence test

IQ gain


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Memory Training

Procedure Treatment group engaged in memory tra

for a half hour every day for weeks See next slide

IQ All subjects completed a test of intelligence

and after training


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Memory Training


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Memory Training


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Memory Training


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Memory Training

Does it really work? Potential confounds?


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Segment Summary

The major benefit of randomizedexperiments is they allow for strong c

about causalityWhy stuff happens! Predict stuff

Prevent bad stuff Promote good stuff


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Segment Summary

Strong causal claims require: True independent variables Random and representative samples No confounds (impossible, but we try ou


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END SEGMENT


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Lecture 1 ~ Segment 3

The concept of random


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Random

Experimental research requires: Random selection Random assignment


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Random

Random selection Individuals included in a sample should b

randomly selected from the population


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Illustration


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Random


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Not random


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Random

Random assignment Individuals are randomly assigned to con


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Random assignmentGroup 1 Group 2


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Segment Summary

Experimental research requires: Random selection Random assignment


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END SEGMENT


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END LECTURE 1

Lecture Slides Stats1.13.L02.AIR

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