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WHS AP Psychology Research Methods: Correlation
I CAN ANSWER • How do psychologists use the scientific method to study behavior and mental processes? • What are the strengths and weaknesses of the different research methods? • How do psychologists draw appropriate conclusions about behavior from research?
Hypothesis is a testable prediction that lets us accept, reject or revise a theory. If families do not stress gender differences then there will be fewer sex differences in siblings.
Theory is an EXPLANATION based on evidence that PREDICTS behaviors or events. A Theory must: 1. Fit the known facts 2. Predict new discoveries 3. Be falsifiable 4. be simple. The simpler the better ! Families influence the gendering of their children.
Research Methods in Psychology • Correlational Research – Research technique based on the naturally occurring relationship between two or more variables – Used to make PREDICTIONS, such as the relation between SAT scores and success at college – Cannot be used to determine cause and effect
Scatterplots Perfect positive correlation (+1. 00) Scatterplot is a graph that comprises of points generated by values of two variables. The slope of points depicts the direction, The amount of scatter shows the strength of relationship.
Scatterplots Perfect negative correlation (-1. 00) No relationship (0. 00) Scatterplot on the left shows a relation between the variables, and the on the right shows no relationship between the two variables.
Correlation When one trait or behavior accompanies another, we say the two correlate. Indicates strength of relationship (0. 00 to 1. 00) Correlation coefficient Correlation Coefficient is a statistical measure of relationship between two variables. r = + 0. 37 Indicates direction of relationship (positive or negative)
Operational Definition • An exact description of how to derive a value for a characteristic you are measuring. It includes a precise definition of the characteristic and how, specifically, data collectors are to measure the characteristic. – If I make silly faces at a subject, then the subject will react in anger. What are “silly faces? ” How do I measure “anger. ” Studies MUST be replicable, so these must be CLEARLY defined! • What you are studying determines the type of data you get.
Study of Low Self Esteem and Depression • You do the research because you assume the two are related • Compare two variables – Variable 1 = Score on a self-esteem test – Variable 2 = Length of a bout of depression in months
–Score on a self-esteem test –Length of a bought of depression in months
Correlation and Causation or
Correlation is not Causation: It only predicts!!!! • Children with big feet reason better than children with small feet. – • (Children who are older have bigger feet than younger children; thus they can reason better) Study done in Korea: The most predictive factor in the use of birth control use was the number of appliances in the home. – (Those who have electrical appliances probably have higher socioeconomic level, and thus are probably better educated. )
Correlation is not Causation: It only predicts!!!! • People who often ate Frosted Flakes as children had half the cancer rate of those who never ate the cereal. Conversely, those who often ate oatmeal as children were four times more likely to develop cancer than those who did not. – Cancer tends to be a disease of later life. Those who ate Frosted Flakes are younger. In fact, the cereal was not around until the 1950 s (when older respondents were children, and so they are much more likely to have eaten oatmeal. )
The Simpsons (Season 7, "Much Apu About Nothing") Homer: Not a bear in sight. The "Bear Patrol" is working like a charm! Lisa: That's specious reasoning, Dad. Homer: [uncomprehendingly] Thanks, honey. Lisa: By your logic, I could claim that this rock keeps tigers away. Homer: Hmm. How does it work? Lisa: It doesn't work; it's just a stupid rock! Homer: Uh-huh. Lisa: But I don't see any tigers around, do you? Homer: (pause) Lisa, I want to buy your rock.
Consider the following research undertaken by the University of Texas Health Science Center at San Antonio appearing to show a link between consumption of diet soda and weight gain. The study of more than 600 normal-weight people found, eight years later, that they were 65 percent more likely to be overweight if they drank one diet soda a day than if they drank none. And if they drank two or more diet sodas a day, they were even more likely to become overweight or obese.
Confounding/Extraneous Variables A relationship other than causal might exist between the two variables. It's possible that there is some other variable or factor that is causing the outcome.
• Ice cream sales and the number of shark attacks on swimmers are correlated. • Skirt lengths and stock prices are highly correlated (as stock prices go up, skirt lengths get shorter). • The number of cavities in elementary school children and vocabulary size are strongly correlated.
CAN I ANSWER • How do psychologists use the scientific method to study behavior and mental processes? • What are the strengths and weaknesses of the different research methods? • How do psychologists draw appropriate conclusions about behavior from research?