master notes soc 200.doc

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University of Toronto St. George
Margaret Gassanov;

15122012 212500Chapter 8ExperimentsThree major pairs of components in an experimentIndependent and Dependent VariableThe independent variable is dichotomous variable having two attributes present or not present in an experimentThey experiment to see what happens when the independent variable is present or not presentIndependent and dependent variables must be operationally defined ie a questionnaire to define what prejudice means Pretesting and Posttesting thats actually how its supposed to be spelledPretesting the measurement of a dependent variable among subjects before they are exposed to a stimulus representing an independent variablePosttesting The remeasurement of a dependent variable among subjects after they have been exposed to a stimulus representing an independent variableExample testing a groups prejudice toward aboriginals pretesting then making them watch a Aboriginal history movie then after having them retested posttesting to see if their attitudes changed after being educated the variableExperimental and Control groupsExperimental groups In experimentation a group of subjects to whom an experimental stimulus is administeredControl group Should resemble the experimental group in every aspect but which does not receive the experimental stimulusUsing a control group allows the researcher to detect any effects of the experiment itself on the subjectsTrying to avoid a great deal of the Hawthorne effect any impact of research on the subject of studyThe Double Blind Experiment An experimental design in which neither the subjects nor the experiments know which is the experimental group and which is the control Selecting SubjectsProbability SamplingUsing a sampling frame select two probability samples that represent the total population of the study and represent each other Seldom used RandomizationRandomly assigning experimental subjects to experimental and control groups1Page 2MatchingThe procedure when pairs of subjects are matched on the basis of their similarities in one or more variables then one member of the pair is assigned to the experimental group and the other to the controlVariation on Experimental Design Donald Campbell and Julian StanleyPreExperimental Research Designs Illustration on page 233 Figure 83OneShot Case Study Surveying people that watched the Aboriginal History movie and the answers to the questionnaire seem to show a low level of prejudice We cant be sure this is true because there is no pretest that proves watching the movie is the independent variable to reducing prejudiceOne Group PretestPosttest Design This now adds a pretest for the experimental group but now lacks a control group can no long tell the effects of being researched on the groupStatic Group Comparison no pretest Showing the Aboriginal History movie to one group and not the other to measure to see if the movie made a difference but the separate groups may have toatally different levels of prejudice coming in that is unknownValidity Issues in Experimental ResearchSources of Internal Validity Internal Validity refers to the possibility that the conclusions drawn from experimental results may not accurately reflect what went on in the experiment itselfThe threat of internal validity is present whenever anything other than the experimental stimulus can affect the dependent variableTwelve of the Several Sources of Internal Validity by Cambpell Stanley and CookHistory The beating of an Aboriginal leader during the time of this experimentMaturation In a long term experiment subjects opinions will grow and have an effect on the experiment In a short one they may grow tired and effect their behavior Testing By testing and retesting many times the subjects will grow to be more sensitive to the issue ands give more thoughtful answers ie dont want to appear prejudiceInstrumentation Using different measures in the pre and posttest questionnaire may bring different outcomes Statistical Regression Like interviewing someone at an extreme example having someone with a low score they can only get better or stay at that level they cant get worseSelection Biases Making an assumption on who should go to one group or another without testing itExperimental Morality If someone drops out of the experiment mid way in it will affect the results 2Page 3Causal Time Order When there is ambiguity about what the dependent and independent variables areDiffusion or Imitation of Treatments When subjects can communicate with each other and pass on ideas or information that could affect the experiment Comprehension When you give something extra to one group and not to the other in real life experiments ie more careCompensatory Rivalry One group knowing there is a difference and trying to work harder to be as good as the other group this one is so stupid idk why they would even know about each other hmmDemoralization If one group feels deprived of an aspect of help Sources of External InvalidityExternal Validity the possibility that conclusions drawn from the experimental results may not be generalizable to the real worldExpectations of the research Group 1 watches the aboriginal movie Group 2 does not Figure 85 page 237In Group 1 the Posttest prejudice should be less than the pretest prejudiceIn Group 2 the Prejudice should be the same in the pretest and posttest In Group 1 posttest should show less prejudice than the Group 2 posttestThe Group 3 posttest should show less prejudice than the Group 4 posttest Natural ExperimentsOccur in the course of social life in the real world and social researchers can implement them in somewhat the same way they could design and conduct laboratory experiments Web Based ExperimentsIncreasingly common for researchers to use the Web as a place to conduct social science experiments Strength and Weaknesses of the Experimental MethodPrimary weakness is Artificiality What happens in the experiment may not reflect what happen in the real outside world The strengths though include scientific rigor the isolation of the independent variable the isolation of the independent and dependent variable which allows causal interference and the ease of replication Chapter 8 ExperimentsThe Classical ExperimentIndependentDependent Variablesdichotomous variablehaving 2 attributes3
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