Research in Psychology


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Psychology, Research, Independent Variable, Dependent Variable, Experimental, Correlation, Cause and Effect

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Research in Psychology

  1. 1. Research in Psychology  Is Empirical (based off observation)  Measures and Describes ( psychological constructs and operational definitions)  Makes a Prediction (formulates a hypothesis about the relationship between 2 or more variables)  Suggests an application (understanding allows control over our environment)
  2. 2. Theories, Hypotheses, and Research  Theories (from the specific to the general)  Hypotheses (from the general to the specific)  Research ( a term for the multiple ways a hypothesis can be tested)
  3. 3. Steps in Scientific Research 1) Establish a testable hypothesis (operational definition must be clear and precise) 2) Design the Study (how you will test and measure the variables of interest) 3) Collect the Data (Could be though direct observation, questionnaires, or behavioral tests) 4) Analyze Data and Suggest an Application (statistical analysis and relevance of research) 5) Report the findings (writing a research report and journal submission)
  4. 4. Experimental Research  Establishes Cause and Effect  Independent Variable (IV): is manipulated  Dependent Variable (DV): is measured  Experimental Group : receives the (IV)  Control Group: receives nothing or placebo
  5. 5. Experimental Research  Population (random selection)  Sample (random assignment)  • • • • Extraneous Variables: are controlled Selection bias (random selection) Assignment bias (random assignment) Experimenter bias (double-blind study) Novelty effects (field study)  Confounding Variables: have an effect on the (DV)
  6. 6. Alleviation of Depression = Dependent Variable Between-Subjects Experimental Design Experimental Group Control Group Receives the IV (antidepressant) Receives nothing (placebo)
  7. 7. Identify the (IV) and the (DV) • A researcher is conducting a study to see if room temperature influences learning. • Of 100 individuals with obsessive-compulsive disorder (OCD), 50 receive 8 weeks of an experimental drug for OCD, while 50 are placed on a waiting list for 8 weeks. At the end of the 8 weeks, all 100 individuals are given psychological tests to assess their level of OCD.
  8. 8. Variations in Experimental Designs Within-Subjects Experimental Design  Some experimental designs do not compare groups. (no random assignment) All members of the sample participate in both control and experimental conditions.  A researcher is evaluating the effects of a study skills class on the GPA scores of college Freshman.
  9. 9. Variations in Experimental Designs Single-Subject Experimental Design Researchers may choose to experiment with a single Participant. (no random selection or random assignment)
  10. 10. Statistical Analysis  The Null Hypothesis (accept or reject)  Type I Error: rejecting a true null hypothesis  Type II Error: accepting a false null hypothesis  The Alpha Level: the probability of chance occurrence • Low Alpha (.01) increased risk of type II error • High Alpha (.05) increased risk of type I error
  11. 11. Advantages and Disadvantages of Experimental Research Advantages  It is the only form of research that can establish cause and effect.  Experiments allow the researcher precise control over variables. Disadvantages  Experiments are often artificial.  Some experiments cannot be conducted due to ethical concerns.
  12. 12. Correlational Research  A Non-experimental form a research that shows a directional relationship between variables.  Correlational Coefficient (numerical value that determines the strength of a relationship between variables between -1 and +1)
  13. 13. Positive Correlation  High scores on X are related to high scores on Y, and low scores on X are related to low scores on Y. X Y Years Smoking Risk of Cancer X Y Years Smoking Risk of Cancer
  14. 14. Negative Correlation  High scores on X are related to low scores on Y, and low scores on X are related to high scores on Y. Y x Amount of cocaine hours of sleep x Amount of cocaine hours of sleep
  15. 15. No Correlation A correlation coefficient of (0) indicates there is no relationship between variables.
  16. 16. Correlational Coefficient Negative Correlation Positive Correlation -1_______________________0______________________+1 Strength of Relationship Increasing Increasing
  17. 17. Advantages and Disadvantages of Correlational Research Advantages  It allows researchers to study variables that would be unethical to manipulate.  Researchers can study variables as they exist naturally. Disadvantages  Correlations are not able to show cause and effect. (no manipulation of the (IV)  They provide little control over extraneous variables.  The direction of the relationship is unclear.