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Psychological Research & Statistics

Psychological Research & Statistics. Chapter 20. Objectives. Describe the process of psychological research Name the different types of psychological research and some of the methodological hazards of doing research Describe descriptive & inferential statistics

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Psychological Research & Statistics

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  1. Psychological Research & Statistics Chapter 20

  2. Objectives • Describe the process of psychological research • Name the different types of psychological research and some of the methodological hazards of doing research • Describe descriptive & inferential statistics • Name specific research methods used to organize data

  3. Key terms • Case study • Central tendency • Control group • Correlation • Correlation coefficient • Cross-sectional studies • Dependent variable • Descriptive statistics • Experimental group • Frequency distribution • Histogram • Independent Variable • Inferential statistics • Longitude studies • Mean • Median • Mode • Naturalistic observation • Normal curve • Population • Range • Sample • Self-fulfilling prophecy • Standard deviation • Statistics • Survey • Validity • Variable • Variance

  4. APA CODE of ETHICS • Informed Consent • Protect subjects from harm • Psychological • Physical • Subjects can withdraw anytime • Debriefing • Subjects anonymous

  5. What do you think? • Amazing Randi

  6. Gathering Data • How do psychologist collect information about the topic they’ve chosen to study? • Social psychologist who is studying the effects of group pressure is likely to conduct an experiment • A psychologist who is interested in personality theories might begin with intensive case studies of individuals • Whatever the approach, decision must be made in advance

  7. Gathering Data: VALIDITY • Stop hair loss • “Freedom from wrinkles” • Huge weight lose in “just 2 weeks!” • Self-help books: (How to achieve the perfect relationship) • Actors playing experts • Task of psychologists is to determine validity: • Validity: The ability of a test to measure what it is intended to measure; verifying a theory • A theory cannot be accepted until it has been repeatedly tested

  8. Gathering Data: SAMPLES • A psychologists wants to know how the desire to get into college affects the attitudes of high-school juniors and seniors. • Would it be possible to test all in the country? • What would the psychologist do? • Sample: The small portion of data, out of the total amount available, that a researcher collects • Population: The total group of subjects from which a sample is drawn

  9. Gathering Data: SAMPLES • Choosing a sample may be tough! • Samples must be representative of the population a researcher is studying • Ex: If you wanted to know how tall American men are, what professional group would you make certain not to have a disproportionately large number of representatives? • NBA basketball players • If you didn’t what would this sample be? • Biased, it would not represent American men in general

  10. Gathering Data: SAMPLES • How to avoid a biased sample? • Take a purely random sample • To ensure that each individual within the scope of the research has an equal chance of being represented • How? • Choose every 20th name on school enrollment lists • Deliberately pick individuals who represent the various subgroups in the population being studied • How? • Research on students, select students of both sexes, varying ages, of all social classes, from all neighborhoods (Stratified sample)

  11. Gathering Data: CORRELATIONS & EXPLANATIONS • Examine a relationship between two sets of observations • EX: Students grades & number of hours they sleep • Correlation: The degree of relatedness between two sets of data

  12. Gathering Data: CORRELATIONS & EXPLANATIONS • What would be the correlation between IQ scores and academic success? • High IQ tend to go with high grades • Low IQ tend to go with low grades • Negative correlation • Smoking cigarettes and living long, healthy life • Student example of correlations?

  13. Experiments • Why would a researcher choose experimentation over other research methods? • Experimentation enables the investigator to control the situation and to decrease the possibility that unnoticed, outside factors will influence the results • What is an experiment designed to do? • Prove or disprove a hypothesis

  14. Experiments • Variables: In an experimental situation, any factor that is capable of change • 2 types of variables • Independent: In an experiment, the factor that is deliberately manipulated by the experimenters to test its effect on another factor; the cause of change • Dependent: The factor, chosen by the experimenter, that may or may not change when the independent variable is changed

  15. Experimental Method • Worksheet • Independent & Dependent variable

  16. Experiments • Experimental group: The group of subjects to which an independent variable is applied • Is there a chance that subjects will act differently because it is an experiment? • Controlled group: Group who is treated in the same way as the experimental group, except the experimental treatment (independent variable) is not applied

  17. Experiments • What is necessary in all experiments? • Control group • What would happen without a control group? • Researcher cannot be sure the experimental group is reacting to- a change in the independent variable

  18. Worksheet • Thinking Drunk, Driving Drunk • Marriage: Practice Makes Imperfect

  19. Naturalistic Observation • Researchers need to understand the way people & animals behave naturally. • Naturalistic observation: Studying phenomena as they occur in natural surroundings, without interfering

  20. Naturalistic Observation • Examples • Psychologists might join a commune • Take position behind a 2-way mirror to watch youngsters play • Live in the jungle to study behavior of gorillas (Gorillas in the Mist) • CARDINAL RULE of Naturalistic Observation: • Avoid disturbing the people or animals you are studying

  21. Walk on the Wild Side! • This is the way we walk

  22. Case Studies • Case study: An intensive investigation of an individual or group, usually focusing on a single psychological phenomenon • Value of case studies? • Provide a wealth of descriptive material that may generate new hypotheses that researchers can then test under controlled conditions with comparison groups

  23. New York University • Investigate the psychological characteristics of people receiving death • 15 inmates • Are death row inmates shrewd, cold killers?

  24. New York University • Findings • All 15 had history of severe head injury • 12/15 showed signs of brain damage • Most are below average IQ

  25. Surveys • Survey: Sampling of data, obtained through interviews and questionnaires • May be impersonal, but most practical way to gather data on the attitudes, beliefs, and experiences of large numbers of people

  26. Surveys

  27. Interviews • Studying people face to face and asking questions

  28. Longitudinal Studies • Longitudinal Studies: Repeatedly gathering data on the same group of subjects over a period of time for the purpose of studying consistencies and changes • Has behavior or feelings changed?

  29. Cross-sectional Studies • Alternative approach to gathering data is Cross-sectional study: Acquiring comparable data subgroups on the basis of certain criteria for the purpose of studying similarities and differences • Ex: Give an IQ test to individuals 30,40, & 60 years old and compare average scores, then draw conclusions about intelligence at various ages

  30. Cross-sectional Studies • Advantages: • Less expensive • Reduce amount of time needed for study • Disadvantage • With the previous example with IQ and age • Example concluded that intelligence declines with age, but age may not be the primary cause of decline • What could have influenced the results? • Education, life experiences, opportunity

  31. Avoiding Errors in doing Research • Self-fulfilling prophecy: A belief, prediction, or expectation that operates to bring about its own fulfillment • How to avoid self-fulfilling prophecy is to use the double-blind technique

  32. Avoiding Errors in doing Research • Single-blind technique • Wants to study the effects of a tranquilizer • One group receives the drug • Other group receives a placebo (harmless substitute for the drug) • Which group is experimental & controlled? • Next step to compare performances on a series of tests • Who is blind in this experiment?

  33. Avoiding Errors in doing Research • How could we make the previous experiment a double-blind experiment? • Both the researcher and the subjects do not know who took the drugs or the placebo • Eliminates the possibility that the researcher will unconsciously find what she expects to find about the effects of the drug

  34. Avoiding Errors in doing Research • Psychologists are like you and I, they have attitudes, feelings, and ideas of their own, and their reactions to different subjects may distort the results of a study. • Researchers may unknowingly react differently to male and female subjects, short and tall subjects, subjects who speak with an accent

  35. Avoiding Errors in doing Research • What would happen if several children being studied in a play area were introduced to a television camera man and said they were going to be on TV tonight?

  36. Statistical Evaluation • How many times have you been told that, in order to get good grades, you have to study? A psychology student named Jolly Mames has always restricted the amount of TV she watches during the week, particularly before a test. She has a friend though who does not watch TV before a test but who still does not get good grades. This fact challenges Jolly’s belief.

  37. Statistical Evaluation • Jolly hypothesizes that, among her classmates, those who watch less TV get better grades, she decides to conduct a survey to test the validity of her hypothesis. • Asks 15 students in her class to write down how many hours of TV they watch the night before their weekly psychology quiz and how many hours they watched on the night after the quiz.

  38. Statistical Evaluation • Jolly collect addition information like checking off familiar products on a list of20 brand name items that were advertised on TV the night before the quiz. Jolly also asks her subjects to give their height • Data is turned in and Jolly is overwhelmed with the amount of information she has collected

  39. Statistical Evaluation • How can it be organized so it will make sense? • How can Jolly analyze it to see whether it supports or contradicts her hypothesis? • Statistics: The branch of mathematics concerned with summarizing and making meaningful inferences from collections of data

  40. Statistical Evaluation • How much television did the two students with the best grades watch the night before the quiz?

  41. Descriptive Statistics • When the study is complete, the first task is to organize the data in as brief and clear a manner as possible. • Jolly must put her responses together in a logical format. When she does she will be using • Descriptive statistics: The listing and summarizing of data in a practical, efficient way, such as graphs and averages

  42. Descriptive Statistics • Distributions of data: • One of the 1st steps is to organize their data is to create frequency tables and graphs. • Tables and graphs provide a rough picture of the data (initial peek of data) • Are scores bunched up or spread out? • What scores occur most often?

  43. Descriptive Statistics • Jolly is interest in how many hours of TV her subjects watched the night before and the night after the quiz. • Jolly uses the numbers of hours of TV viewing as categories and then she counts how many subjects reported each category of hours before and after the quiz. • Jolly has created a table • Frequency distribution: An arrangement of data that indicates how often a particular score or observation occurs

  44. Jolly’s Frequency Table

  45. Quiz: Understanding Research • Video

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