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Published byErica Hunt Modified over 8 years ago
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How Psychologists Ask and Answer Questions EXPERIMENTATION
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What you need to know before the end of these notes…. ● Identify independent, dependent, confounding, and control variables in experimental designs. ● Distinguish between random sample/selection of participants and random assignment in experiments.
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Like other sciences, experimentation forms the backbone of research in psychology. Examples of famous experiments: ● Pavlov’s salivating dogs ● Milgram’s obedience study ● Asch’s conformity experiment Exploring Cause and Effect Experiments are the only research method that isolates cause and effect!
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EXPERIMENT Hypothesis (testable prediction… Caffeine helps keep high school teachers alert and happy. Want to test the effects of caffeine on the behavior of high school teachers At this point…researchers will create operational definitions of the various aspects of their experiment.
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Who is your population? ● HS teachers!! o More specifically…Myers Park High School teachers ● Need a representative sample (a smaller group that gives a “snapshot” of the total population) o What would that look like at MPHS? o How do you obtain this representative sample?
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Types of Samples ● Random Sample (every one in the population has an equal chance of being selected) o Put all of the teachers names into a hat and draw out 60 names ● Stratified Sample (the population is divided into relevant subcategories & a random sample is taken from each subcategory) o Divide the staff into categories…male/female, new/veteran teachers, subject areas, etc…
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Control vs. Experimental Groups ● Experimental group (group that receives special treatment) o Group A - participants drink two cups of regular (caffeinated) coffee every morning for a month ● Control group (comparison group(s)) o Group B - participants drink two cups of decaf coffee every morning for a month o Group C - participants drink hot, brown, coffee flavored water for a month
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Random Assignment ● Once a sample is obtained, researcher randomly assigns participants to the experimental or control groups ● Assigning participants to experimental and control conditions by random assignment minimizes pre-existing differences between the two groups *How do we do this in our experiment? o After participants have gathered, hand out numbered cards in no particular order to all to separate into control and experimental groups
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Independent vs. Dependent ● Independent variable (cause) o the factor manipulated by the experimenter whose effect is being studied. o In our experiment… Type of drink…caffeinated, decaffeinated, water ● Dependent variable (effect) o the factor that may change in response to independent variable. In psychology it is usually a behavior or a mental process. o In our experiment… Behavior – alertness, crankiness, etc. How measure? Teachers fill-out questionnaire at beginning to get baseline data and at the end of each day for the month
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Placebo ● Pseudotreatment…fake treatment ● Why have a placebo? o To test true effects of independent variable…sometimes beliefs of participants can alter behavior ● What is the placebo in our experiment? o Decaffeinated coffee o Coffee flavored water
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Single-blind vs. Double-blind ● Single-blind o Teachers (participants) do not know which group they are in ● Double-blind o Teachers (participants) nor person gathering data know which group is control or experimental group ● Which is “better”? Why?
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Confounding Variables ● Other items that could effect the outcome of the experiment (other than the independent variable alone) ● What could be some confounding variables in our experiment? o Still some caffeine in decaf coffee o Experience with coffee prior to experiment (i.e. whether or not regular coffee drinker) o Amount of sleep
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