Psychology Chapter 2


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Psychology Chapter 2

  1. 1. Chapter 2 Psychological Research Methods and Statistics
  2. 2. Section 1 What is Research?
  3. 3. Jane Goodall <ul><li>Observed chimpanzees in Tanzania, Africa for more than 30 years </li></ul><ul><li>she used the research method of naturalistic observation </li></ul><ul><li>Collect information like most people do in everyday life-only more carefully and more systematically </li></ul>
  4. 4. Pre-Research Decisions <ul><li>Must ask a specific question about a limited topic or hypothesis </li></ul><ul><li>The method or research depends on the research topic </li></ul><ul><li>It does not matter what approach the data is collected, but decisions need to be made ahead of time </li></ul>
  5. 5. Samples <ul><li>A sample is the small group of participants, out of the total number available, that a researcher studies </li></ul>
  6. 6. Methods of Research <ul><li>Naturalistic observation- research method in which the psychologist observes the subject in a natural setting without interfering </li></ul><ul><li>Case study- research method that involves an intensive investigation of one or more participants </li></ul>
  7. 7. Methods of Research <ul><li>Surveys- research method in which information is obtained by asking many individuals a fixed set of questions </li></ul><ul><li>Longitudinal study- research method in which data are collected about a group of participants over a number of years to access how certain characteristics change or remain the same during development. </li></ul>
  8. 8. Methods of Research <ul><li>Cross-sectional study- research method in which data are collected from groups of participants of different ages and compared so that conclusions can be drawn about differences due to age. </li></ul><ul><li>Correlation-the measure of a relationship between two variables or sets of data </li></ul>
  9. 9. Experiments <ul><li>Hypothesis- an educated guess about the relationship between two variables </li></ul><ul><li>Variable- any factor that is capable of change </li></ul><ul><li>Experimental group- the group to which an independent variable is applied </li></ul><ul><li>Control group- the group that is treated in the same way as the experimental group except that the experimental treatment (the independent variable is not applied. </li></ul>
  10. 10. Ethical Issues <ul><li>Ethics- the methods of conduct or standards, for proper and responsible behavior </li></ul><ul><li>Using animals in research has become an issue in recent years </li></ul>
  11. 11. Section 2 Problems and Solutions in Research
  12. 12. Self-fulfilling Prophecy <ul><li>Is a situation in which a researcher’s expectations influence that person’s own behavior, and thereby influence the participants behavior. </li></ul>
  13. 13. Avoiding a Self-fulfilling Prophecy <ul><li>Single-blind experiment- is an experiment in which the participants are unaware of which participants received the treatment </li></ul><ul><li>Double-blind experiment- is an experiment in which neither the experimenter nor the participants know which participants received which treatment </li></ul><ul><li>By conducting this type of experiment the researcher can remain unbiased. </li></ul>
  14. 14. The Milgram Experiment <ul><li>Stanley Milgram wanted to determine whether participants would administer painful shocks to others because an authority figure instructed them to do so </li></ul><ul><li>He gathered 1000 participants </li></ul><ul><li>The volunteers were paired with learners </li></ul><ul><li>The volunteer would shock the learner when the learner made a mistake </li></ul>
  15. 15. The Milgram Experiment <ul><li>The volunteers were told that with each mistake, the electrical shock would become stronger </li></ul><ul><li>The volunteers did not realize the shocks were fake </li></ul><ul><li>65% of the volunteers pushed the shock button until it reached maximum severity </li></ul><ul><li>Proved that ordinary individuals could easily inflict pain if orders were given by a respected authority </li></ul>
  16. 16. The Milgram Experiment <ul><li>Was an excellent example of a single-blind experiment </li></ul><ul><li>Swarthmore College conducted the same study </li></ul><ul><li>88% of undergraduates administered the highest level of shock </li></ul>
  17. 17. The Placebo Effect <ul><li>Is a change in a participant’s illness or behavior that results from a belief that the treatment will have an effect rather than from the actual treatment </li></ul><ul><li>Psychiatric patients in two study groups were given a drug, after a six-week period the groups were evaluated </li></ul>
  18. 18. The Placebo Effect <ul><li>53% to 80% reported they benefited from the drugs </li></ul><ul><li>The drugs administered were placebos </li></ul><ul><li>The people reacted to their own expectations of how the drug given would affect them. </li></ul><ul><li>Neither the researchers or the patients new they were placebos until after the experiment </li></ul>
  19. 19. Section 3 Statistical Evaluation
  20. 20. Statistics <ul><li>The branch of mathematics concerned with summarizing and making meaningful inferences from collections of data </li></ul><ul><li>Descriptive Statistics- the listing and summarizing of data in a practical, efficient way </li></ul>
  21. 21. Distributions of Data <ul><li>Frequency distribution- an arrangement of data that indicates how often a particular score or observation occurs </li></ul><ul><li>Find the percentage </li></ul><ul><ul><li>Divide the frequency of the participants within a category by the total number of participants and multiplying times 100. </li></ul></ul>
  22. 22. Distributions of Data <ul><li>Histograms- similar to bar graphs, except they show frequency distribution by means of rectangles whose widths represent class intervals and whose areas are proportionate to the corresponding frequencies </li></ul>
  23. 23. Distributions of Data <ul><li>Frequency polygons </li></ul><ul><ul><li>Are useful because they provide a clear picture of the data distribution </li></ul></ul><ul><li>Normal curve (bell-shaped curve) </li></ul><ul><ul><li>a graph of frequency distribution shaped like a symmetrical, bell-shaped curve; a graph normally distributed data </li></ul></ul><ul><ul><li>Curve is symmetrical </li></ul></ul><ul><ul><li>Can divide the curve into sections to determine what percentage falls into each area </li></ul></ul>
  24. 24. Measures of Central Tendency <ul><li>Is a number that describes something about the “average” score of a distribution </li></ul><ul><li>Mode- the most frequent score </li></ul><ul><li>Bimodal- distributions with two modes </li></ul><ul><li>Median- is the middle score (least to most) </li></ul><ul><li>Mean- usually referred to as the average and commonly used measure of central tendency (add all scores and divide by total number of scores) </li></ul>
  25. 25. Measures of Variability <ul><li>Variability- a measure of difference, or spread of data </li></ul><ul><ul><li>Range- subtract the lowest score from the highest score and add 1. </li></ul></ul><ul><ul><li>Standard deviation- a measure of variability that describes an average distance of every score from the mean. </li></ul></ul><ul><ul><ul><li>Scores above the mean are positive, below are negative </li></ul></ul></ul><ul><ul><ul><li>Larger the SD, the more spread out the scores </li></ul></ul></ul>
  26. 26. Correlation coefficient <ul><li>Describes the direction and strength of the relationship between two sets of variables </li></ul><ul><ul><li>(+) as one variable increases the second variable increases </li></ul></ul><ul><ul><li>(-) as one variable increases, the other variable decreases </li></ul></ul><ul><ul><li>Scatterplot- is a graph of participants’ scores on the two variables, and it demonstrates the direction of the relationship between them </li></ul></ul>
  27. 27. Inferential Statistics <ul><li>Numerical methods used to determine whether research data support a hypothesis or whether results were due to chance </li></ul><ul><li>Probability and Chance </li></ul><ul><li>Statistical significance </li></ul>
  28. 28. Source: <ul><li>Kasschau, Richard, A. Understanding Psychology . McGraw-Hill, Glencoe, New York, New York, 2008. </li></ul>