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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.)