Research Methods

Reasoning Fallacies Hindsight bias Tendency to believe, after learning an outcome, that one would have foreseen it The “I knew it all along” phenomenon Ex: After the Packers lost on Sunday, people thought, “I knew all along they’d lose.” – even if they didn’t

Overconfidence Tendency to think we know more than we do EX: Thinking you did better on a quiz than you actually did

Ethics In conducting an experiment, psychologists must Obtain informed consent of participants Protect them from harm and discomfort Treat info about participants confidentially Fully explain research afterward

Testing hypotheses with descriptive methods Case study - studies one person in depth in hopes of revealing universal principles EX: studying a patient with a specific mental disorder

Survey - uses a representative sample of people to estimate attitudes or reported behaviors of a whole population Population - all the cases in a group being studied from which samples may be drawn Random sample - every member of a population has an equal chance of inclusion

Practice At the end of the first two weeks of the baseball season, newspapers start publishing the top ten batting averages. The leader after the first two weeks normally has a batting average of .450 or higher. Yet no major league baseball player has ever finished the season with a better than .450 average. What do you think is the explanation for the fact that batting averages are higher earlier in the season?

Importance of Sample Size Imagine you are a golfer of above-average ability and that you have the opportunity to play the greatest golfer in the world. If you want to maximize your slim chance of winning, how much golf would you elect toplay, g iven the choices of 1, 18, 36 or 72 holes?

A certain town is served by two hospitals A certain town is served by two hospitals. In the larger hospital about 45 babies are born each day, and in the smaller hospital about 15 babies are born each day. Although the overall proportion of boys is about 50%, the actual proportion at either hospital may be greater or less than 50% on any day. At the end of a year, which hospital will have the greater number of days on which more than 60% of the babies born were boys? The larger hospital The smaller hospital Neither – the number of days will be about the same (within 5% of each other)

Naturalistic observation - observing and recording behavior in a natural environment Studying gorillas in the wild or high school behavior in the lunch room Advantage: Can observe someone in his natural environment Disadvantages: Reactivity subject’s behavior is different when the person knows he is being observed than it would otherwise be Single cases may be misleading

Correlational studies Measure how closely two things vary together and thus how well either one predicts the other Graphed on a scatterplot and measured with a correlation coefficient Positive = two sets of scores rise or fall together Negative = two sets of scores relate inversely zero = weak correlation

CORRELATION DOES NOT PROVE CAUSATION EX: Self-esteem and depression are negatively correlated. Which is causation? Is a third factor (heredity, age) to blame?

Illusory correlation: The perception of a relationship where none exists EX: It always rains after you wash your car.

Experimentation: in psychology, a study where variables are manipulated to determine a casual outcome Random assignment - assigning participants to experimental and control groups by chance Double blind procedure - neither the research participants nor the research staff know whether participants have received the treatment or a placebo

Placebo effect - experimental results caused by expectations alone EX: A drug/treatment works simply because the participant believes it will

EXPERIMENTAL EXAMPLE Experimental terms using the hypothesis: Breast feeding increases intelligence Experimental group - group exposed to treatment Babies who are breastfed Control group - group not exposed to treatment Babies who are bottle fed

Independent variable (IV) - experimental factor that is manipulated Breast fed or bottle fed Confounding variable - factor other than the IV that might produce an effect in an experiment Environment, diet, wealth Dependent variable - outcome factor; variable that may change in response to manipulations of the IV Intelligence

Statistical significance - observed difference is likely not due to chance variation between the samples