1. What is the difference between positive and negative correlations?

Transcription

1 1. What is the difference between positive and negative correlations? 2. Can correlations make predictions? 3. Can correlations prove causation? 4. What are illusory correlations?

2 We can take data from our description methods (surveys and naturalistic observations) and try to find relationships Correlation measures how things relate to each other, how things vary together How well one thing predicts the other

3 Positive correlation is when both variables increase or decrease together.

4 Negative correlation means that as one variable increases the other decreases. -negative correlation does NOT mean they are LESS correlated, the correlation is just as strong as a positive one

5 1. The more young children watch TV, the less they read. 2. The more sexual content teens see on TV, the more likely they are to have sex. 3. The longer children are breast-fed, the greater academic achievement. 4. The more often adolescents eat breakfast, the lower their body mass.

6 A statistical index of the relationship between two things. From -1 to +1 A weak correlation is close to 0 No correlation is 0 The closer you are to one the more correlated two things are.

7 A graphed cluster of dots which represents the values of two variables. The slope of the points suggests the direction of the relationship between the two variables. The amount of scatter suggests the strength of the correlation (little scatter indicated high correlation)

8 No matter how strong a correlation coefficient, correlation DOES NOT PROVE CAUSATION! Example: High Ice Cream sales are correlated with Murder Rates (they don t effect each other, both are effected by a 3 rd variable: ) Example: Among men length of marriage correlates positively with hair loss. (As you age you lose hair AND are married longer!) There are always outliers on scatterplots

9 The idea of a relationship where none exists. If we believe there is a relationship among 2 things, we are likely to notice and recall instances that confirm our belief. Superstitions Stereotypes (things we see in the real world convince us that a correlation might exist, but in reality there is no correlation)

10 We have a natural eagerness to make sense of our world and a rage for order We look for it in random data Random sequences, streaks, and patterns do occur But they equal out over time and trials What about the woman that won the lottery twice? Some day some how, this was bound to happen, considering how many millions of people play If something is only likely to happen to one in a billion people on any given day do the math that means it will happen 6 times a day, thousands of times a year!

11 1. How do experiments clarify cause and effect? 2. How do we set up the perfect experiment? 3. How does the placebo effect work? 4. If you were a professional research psychologist or scientist, what hypotheses would you want to explore?

12 A research method in which an investigator manipulates one or more factors to observe their effect on some behavior or mental process. Manipulate the factors we are interested in. Control all other factors

13 Only an experiment can determine cause and effect! Experiments enable researchers to manipulate the factor at interest, while controlling other factors.

14 Assigning participants to experimental and control groups by chance. Through this, you reduce the risk of researcher bias as well as minimizing the preexisting differences among those assigned to different groups. Roughly equalizes the two groups in age, attitudes, and every other characteristic.

15 Single-blind Procedure Participant is unaware of placement in experimental or control group Double Blind Procedure Both the research participants and the research staff are ignorant to the expected outcome of an experiment. This procedure is used to control for confounding variables.

16 Placebo A non-active substance or condition that may be administered instead of a drug or active agent to see if the drug has an effect beyond the expectations produced by taking it Placebo Effect experimental results caused by expectations alone. Interestingly enough the more expensive a placebo is the more effective it seems to be.

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18 The group that receives the treatment is the experimental group. The group that does not receive the treatment is the control group.

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20 Independent Variable (IV) researcher actively manipulates, will cause a change in the dependent variable IV causes something to happen Dependent Variable (DV) influenced by the IV, and impact can be measured Should show the effect of the independent variable

21 A factor other than the independent variable that might produce and effect in the experiment.

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