Research Methods Chapter 11 – Flashcards
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maturation threat
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a threat to internal validity that occurs when an observed change in an experimental group could have emerged more or less spontaneously over time
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history threat
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a threat to internal validity that occurs when it is unclear whether a change in the treatment group is caused by the treatment or by a historical factor or event that affects everyone or almost everyone in the group
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regression threat
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a threat to internal validity related to regression to the mean, a phenomenon in which any extreme finding is likely to be closer to its own typical, or mean, level the next time it is measured
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attrition threat
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in a repeated measures design or quasi experiment, a threat to internal validity that occurs when a systematic type of participant drops out of a study before it ends
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instrumental threat
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a threat to internal validity that occurs when a measuring instrument changes over time from having been used before
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selection-history threat
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a threat to internal validity in which members are likely to drop out of either the treatment group or the comparison, not both
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selection-attrition threat
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a threat to internal validity in which members are likely to drop out of either the treatment group or the comparison g group, not both
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observer bias
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a bias that occurs when observers expectations influence their interpretation of the participants behaviors or the outcome of the study
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demand characteristics
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a threat to internal validity that occurs when some cue leads participants to guess a study's hypotheses or goals
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double blind study
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a study in which neither the participants nor the researchers who evaluate them know who is in the treatment group and who is in the comparison group
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masked design
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a study design in which the observers are unaware of the experimental conditions to which participants have been assigned
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double blind placebo controlled study
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a study that uses a treatment group and a placebo group and in which neither the research staff nor the participants know who is in which group
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null effect
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a finding that an independent variable did not make a difference in the dependent variable; there is no significant covariance between the two
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ceiling effect
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an experimental design problem in which independent variable groups score almost the same on a dependent variable, such that all scores fall at the high end of their possible distribution
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floor effect
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an experimental design problem in which independent variable group score almost the same on a dependent variable, such that all scores fall at the low end of their possible distribution.
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manipulation check
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in an experiment, an extra dependent variable researches can include to determine how well an experimental manipulation worked
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noise
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the unsystematic variability among the members of a group in an experiment
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measurement error
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the degree to which the recorded measure for a participant on some variable differs from the true value of the variable for that participant. measurement errors may be random, if over a sample they both inflate or deflate true scores, or they may be systematic in which case they may result in biased measurement
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situation noise
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unrelated events or distractions in the external environment that create unsystematic variability within groups in an experiment
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power
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the likelihood that a study will show a statistically significant result when some effect is truly present in the population; the probability of not making a type 2 error
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Which of the following is NOT one of the three most common threats to internal validity
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floor effects
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Emma is planning an experiment to examine whether reading to children increases their vocabulary size. She plans to measure the vocabulary size of a group of 18-month-olds, read to them three times a week for three months, then measure their vocabulary size again. How could Emma change the design of the study to remove a major threat to internal validity
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She could add a comparison group
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Which of the following is NOT a problem that may contribute to a null effect in a study
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large sample size
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What two types of validity in an experiment can observer bias threaten
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internal validity and construct validity
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An instructor hypothesizes that doing jumping jacks will improve his students' quiz performance. On Monday, he has his class sit in their chairs for five minutes before completing a multiple-choice quiz on their reading assignment. On Wednesday, he has his class do two minutes of jumping jacks before completing the same quiz that they took on Monday. The students performed better on the quiz on Wednesday. What is a possible threat to internal validity in this study
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testing threat
