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Questions. I have had some professors who have a preference on APA style, is the library website a good source for APA format? Do you have a particular preference? What are the consequences if a researcher does not behave ethically towards individuals?

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questions
Questions
  • I have had some professors who have a preference on APA style, is the library website a good source for APA format? Do you have a particular preference?
  • What are the consequences if a researcher does not behave ethically towards individuals?
  • How do you determine the sample size in a given research study?
  • How do you know whether or not the chosen sample is representative of the target population?
more questions
More Questions
  • How do you know if you are inflicting any psychological harm on subjects in animal research? (such as in a controlled lab experiment and not just in observation).
  • In the abstract of a research report, do you need to separate the sections into background, methods, results, conclusions or can you make it one paragraph?
  • If a research has to ethically release all information to a participant before an experiment, how can you ethically run a double blind study where the participant has no idea what is being done.
more questions1
More Questions
  • How can the way in which results are reported become an ‘ethical issue’ of the research process?
  • To do a research, you have to take the Ethics code test. Do you have to retake the test for every research study/experiment that you do or do you only have to take it once?
research strategies and validity

Research strategies and validity

Chapter 6

Dusana Rybarova

Psyc 290B

May 22 2006

outline
Outline
  • Introduction to research strategies
  • Validity and its threats

- internal validity

- external validity

  • Research strategies, research designs and research procedures
1 introduction to research strategies
1. Introduction to research strategies
  • research strategy
    • reflects the general approach and goals of a research study
  • types of research strategies
    • descriptive strategy
    • Nonexperimental strategy
    • correlational strategy
    • experimental strategy
    • quasi-experimental strategy
1 introduction to research strategies1
1. Introduction to research strategies
  • Descriptive strategy
    • the goal is to describe the state of affairs at the time of the study
    • measures variables as they exist naturally
    • e.g. 19% of eligible voters participated in the election
  • Correlational strategy
    • measures two variables, usually as they exist naturally
    • the goal of this strategy is to describe a relationship between the two variables without attempting to explain the cause of the relationship
    • e.g. Are students GPA’s related to their parent’s income?
  • Nonexperimental strategy
    • Answers questions about the relationship between two variables by demonstrating a difference between two groups or two threatment conditions
    • E.g. verbal scores of 6-years old boy and 6-years old girls
1 introduction to research strategies2
1. Introduction to research strategies
  • Experimental strategy
    • the researcher manipulates one variable (called independent variable) while observing or measuring a second variable (dependent variable)
    • this is the ‘true’ experiment because independent variable is manipulated by the researcher (e.g. room temperature)
    • the goal of experimental strategy is to determine whether a causal relationship exists between two variables
1 introduction to research strategies3
1. Introduction to research strategies
  • Quasi-experimental strategy
    • uses a nonmanipulated variable to define groups or conditions (e.g. time or age) or pre and post threatment
    • controls other variables as much as possible
    • the goal is to obtain evidence in support of a cause-and-effect relationship
    • however, a quasi-experimental strategy can not unambiguously establish a causal relationship
2 validity and its threats
2. Validity and its threats
  • validity is the standard criterion by which researchers judge the quality of research
  • in this case the concept of validity applies to an entire research study
  • any component of a research study that introduces questions or raises doubts about the quality of the research process or the accuracy of the research results is a threat to validity
2 validity and its threats1
2. Validity and its threats
  • Internal validity
    • is concerned with factors within the research study that raise doubts about the results or the interpretation
    • any factor within the study that allows an alternative explanation for the results is a threat to internal validity
    • e.g. example with room temperature and performance
2 validity and its threats2
2. Validity and its threats
  • threats to internal validity
    • Extraneous variables
      • any variable in a research study other than the two variables being studied (both systematic and unsystematic)
        • unsystematically changing variables are usually not a problem
      • confounding variable is an extraneous variable that is allowed to change systematically along with the two variables being studied (e.g. time of the day in the temperature-performance study)
2 validity and its threats3
2. Validity and its threats
  • threats to internal validity
    • sources of extraneous/confounding variables
      • participant variables
        • assignment bias – when the process used to assign different participants to different threatments produces groups of individuals with noticeably different characteristics (e.g. one group is smarter, more motivated)
      • environmental variables
        • size of room, time of day, or gender of the experimenter
      • measurement variables
        • practice effects – prior exposure to a measurement procedure provides participants with additional skills that produce improved scores (e.g. the same exam)
        • fatigue – prior participation tires the participants so that their scores on subsequent measurements are lower
2 validity and its threats4
2. Validity and its threats
  • External validity
    • concerns the extent to which the results obtained in a research study hold true outside the constraints of the study
    • Can the results be generalized to other populations, other settings, other measurements?
    • e.g. can we generalize results from a well-controlled laboratory situation to the uncontrolled chaos of the real world?
2 validity and its threats5
2. Validity and its threats
  • threats to external validity
    • Participants
      • characteristics unique to a specific group of participants in a study may limit ability to generalize the results to individuals with different characteristics
        • e.g. college students, volunteer bias, cross-species generalizations
    • Features of the study
      • characteristics unique to the specific procedures used in a study may limit ability to generalize the results to situations where other procedures are used
        • e.g. novelty effect, reactivity, specifics of the study (masking experiments, lexical decisions)
2 validity and its threats6
2. Validity and its threats
  • threats to external validity
    • experimenters
      • characteristics unique to the specific experimenter conducting the study may limit ability to generalize the results to situations with a different experimenter
        • e.g. experimenter bias, experimenter characteristics
    • measurements
      • characteristics unique to the specific measurement procedure may limit ability to generalize the results to situations where a different measurement procedure is used
        • e.g. sensitization (the impact of being assessed), generality across different measures (heart beat vs. questionnaire), time of measurement
2 validity and its threats7
2. Validity and its threats
  • Balancing internal and external validity
    • attempts to increase internal validity can reduce external validity (laboratory experiments)
    • research that attempts to gain a high level of external validity will often create a research environment that closely resembles the outside world
    • there tends to be a tradeoff between internal and external validity (if you increase internal validity, external validity decreases a vice versa)
2 validity and its threats8
2. Validity and its threats
  • Validity of individual research strategies
    • descriptive strategy
      • high external validity
      • low internal validity
    • Nonexperimental strategy
      • High external validity
      • Low internal validity
    • correlational strategy
      • high external validity
      • low internal validity
2 validity and its threats9
2. Validity and its threats
  • Validity of individual research strategies
    • experimental strategy
      • high internal validity
      • low external validity
    • quasi-experimental strategy
      • higher internal validity than descriptive and correlational studies
      • lower internal validity than true experiments
      • relatively high external validity
3 research strategies research designs and research procedures
3. Research strategies, research designs, and research procedures
  • Research strategy
    • refers to the general approach and goals of the study
  • Research design
    • general plan for implementing a research strategy (e.g. group versus individual, same individuals vs. different individuals, number of variables included)
  • Research procedure
    • an exact, step-by-step description of a specific research study (exact involvement of individuals, measurement of variables etc.)
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