Research Methods 2 85 96 Random Selection Every person in the population has an equal chance of being chosen to participate Reduces selection bias Example Hite Report Representative Samples What makes a good experiment Random Assignment No A placebo control group A design Random Selection Reliable and Valid Measures Reliability Consistency of measurement Types of reliability Validity Assessing what intending to assess Reliability and Validity Reliability necessary for Validity not necessary for Let s do an experiment Synthia s Hypothesis Chocolate improves memory Flaws in my experiment Can we draw any conclusions from my experiment Measurements What kinds of measurements can we use Self Report Measures Pros Easy Emotional Information Cons Insight assumed Honesty Response Sets items Examples Tendencies to answers to Positive impression management Malingering Ratings Other people rate someone s behavior Ratings Rate people on the following traits from 1 to 10 with 1 being the lowest of the trait ex very unattractive and 10 being the highest ex very attractive 1 Attractiveness Intelligence Kindness Morality 2 Attractiveness Intelligence Kindness Morality 3 Attractiveness Intelligence Kindness Morality 4 Attractiveness Intelligence Kindness Morality Cons to Ratings Halo Horns Effect positive or negative ratings on one characteristic influence ratings of other characteristics Leniency Effect Error of Central Tendency Ethical Guidelines Why do we need ethical guidelines We are studying people Abuses have happened in the past Example Ethical Guidelines Institutional Review Boards IRB Informed Consent Debriefing APA code of ethics http www apa org ethics code2002 html Milgram Obedience Experiments Was this study ethical Animal Research of psych experiments use animals Regulated by scientific community research institutions and federal government Generally used when no alternatives exist million lab animals die a year Animal Research Adds to our knowledge of psychological processes Allows development of new drugs and other treatments Ethics in Animal Research Is it ethical to test drugs on animals Or to lesion animal s brains to study different diseases Why or why not alternatives For more info If you think it is unethical what are other http www apa org science animal2 html http www mathxl com info MediaPopup aspx origin 1 disciplineGroup 5 type Watch loc MPLspvideo animal rights flv width 1 height 1 autoh yes centerwin yes Statistics Descriptive Statistics Measures of Central Tendency Mean add all of the scores and divide by the number of scores Median the number Mode the number that appears the Example Age of females in this class 19 18 21 18 19 18 19 18 18 18 20 18 19 19 18 Mean 19 18 21 18 19 18 19 18 18 18 20 18 19 19 18 15 Median 18 18 18 18 18 18 18 18 19 19 19 19 19 20 21 Example Departments of upperclassmen Engineering Exploration Program Humanities Biological Sciences Business Biological Sciences Education and Human Ecology Social Behavioral Sciences Mode Dispersion How loosely or tightly bunched scores are Types of Dispersion Range high score low score Standard deviation takes into account from the mean mean mean y y Small SD Large SD x x Inferential Statistics Allow us to determine whether we can our sample findings to a larger population or whether they occurred by chance alone Statistical Significance Findings that would occur by chance alone less than 5 percent of the time More likely with larger sample size With a very large sample will always occur Practical Significance The importance of findings in the Example With N 2 000 a drug decreases the symptoms of depression on average by 0 25 symptoms Take Home Point The scientific method allows us to study things more Types of Research Naturalistic Observations Case Studies Correlational Designs Experiments Experiments must have Experiments can still have bias Bias can be reduced by Take home points Reliability measures consistency and validity measures if it measures what it s supposed to We can measure things by ratings Ethics is particularly important in and self report psychology Statistics can be misleading
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