Extraneous variables demand characteristics demand

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Extraneous Variables Demand Characteristics: Demand characteristic: Experimental design element or procedure that unintentionally provides subjects with hints about the research hypothesis. Demand effect: Occurs when demand characteristics actually affect the dependent variable. Reducing Demand Characteristics: Use an experimental disguise. Isolate experimental subjects. Use a “blind” experimental administrator. Administer only one experimental treatment level to each subject. Types of Experimental Research: Pre-experimental Designs: single or multiple groups are observed subsequent to the treatment that will cause change True Experimental Designs: subjects are randomly assigned to the treatment conditions (levels of the independent variable). The only differences in the groups would be due to chance. Excellent for showing cause and effect relationships. Quasi-experimental Designs – Factorial Designs: experiments that do not involve random allocation of subjects to treatment combinations. One shot Design (after only design): This one-shot design is a case study of a research project fraught with problems. Subjects or test units participate because of voluntary self-selection or arbitrary assignment, not because of random assignment. The study lacks any kind of comparison or any means of controlling extraneous influences. Sometimes it is the only viable choice. One group Pretest-Posttest design: This one-group pretest– posttest design offers a comparison of the same individuals before and after training. Although this is an improvement over Downloaded by:: bryce0736 | [email protected] Distribution of this document is illegal
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Stuvia.com - The study-notes marketplace the one-shot design, this research still has several weaknesses that may jeopardize internal validity. While there will be some problems of internal validity, the researcher must always take into account questions of time and cost. Static group design: The experimental group is measured after being exposed to an experimental treatment and the control group is measured without having been exposed to this experimental treatment. A majour weakness is lack of assurance. Practical Experimental Design Issues: Basic vs Factorial Basic Designs: In basic experimental designs a single independent variable is manipulated to observe its effect on a single dependent variable. Factorial experimental designs are more sophisticated than basic experimental designs and allow for an investigation of the interaction of two or more independent variables. Laboratory Experiments: The researcher has more complete control over the research setting and extraneous variables (artificial environmental setting) Field Experiments: Research projects involving experimental manipulations that are implemented in a natural environment (natural environmental setting) Within-subject and Between-subject Design: Within-subjects design: Involves repeated measures because with each treatment the same subject is measured.
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