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Essential Question. 1-5 How do psychologists draw appropriate conclusions about behavior from research?. ?The root of the problem is that in real life, all scientists ever observe are samples.? And, in real life, all they want to know about is populations" Nancy Darling, Ph.D.. The Importance of Sampling in Research.
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2. Essential Question 1-5 How do psychologists draw appropriate conclusions about behavior from research?
3. “The root of the problem is that in real life, all scientists ever observe are samples. And, in real life, all they want to know about is populations” Nancy Darling, Ph.D.
4. The Importance of Sampling in Research Sample
Small representative subset of a larger population
Random sample
Every subject had equal chance of being selected
Representative sample
Characteristics of participants correspond to larger population
Example: If we know approximately 15% of the United States’ population is of Hispanic descent, a sample of 100 Americans also ought to include around 15 Hispanic people to be representative.
5. You want to make a claim about a WHS student. What is the Population?
All WHS Students
What will be the sample?
The participants in the sample
How could you obtain a random sample?
Get the student list from the office and pick every 10th student.
Pull names out of a hat?
Why might you want a representative sample
A random sample won’t account for small populations
Ethnic Groups
AP Students
Transitional Students
Students in Life Skills
6. Survey From a population if each member has an equal chance of inclusion into a sample, we call that a random sample (unbiased). If the survey sample is biased, its results are wrong.
7. Sampling in Surveys Women and Love study done by Shere Hite 1974
98% Dissatisfied by their Marriage
75% Extramarital Affairs
But to all of those who were mailed surveys only 4% responded.
8. When randomly sampled 93% of women are satisfied in their marriages
Only 7% had affairs
9. Making Inferences Representative samples are better than biased samples.
Less variable observations are more reliable than more variable ones.
More cases are better than fewer cases. OBJECTIVE 19| Identify three principles for making generalizations from samples.
OBJECTIVE 19| Identify three principles for making generalizations from samples.
10. Making Inferences When sample averages are reliable and the difference between them is relatively large, we say the difference has statistical significance.
For psychologists this difference is measured through p value below .05 OBJECTIVE 20| Explain how psychologists decide whether differences are meaningful.
OBJECTIVE 20| Explain how psychologists decide whether differences are meaningful.
11. Random Assignment 100 Volunteers for an experiment
How do you choose which ones will be in the control group?
12. Essential Question 1-5 How do psychologists draw appropriate conclusions about behavior from research?