Ch. 11 Flashcards
What is attrition threat?
In a pretest/posttest +, repeated measures, or quasi-experiment study, a threat to internal validity that occurs when a systematic type of participant drops out of the study before it ends
What is the ceiling effect?
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
What are demand characteristics?
a cue that leads participants to guess a study’s hypothesis or goals; a threat to internal validity
What is a double-blind placebo control study?
a study that uses a treatment group and placebo group and in which neither the researchers nor the participants know who is in which group
What is the floor effect?
an experimental design problem in which independent variable groups score almost the same on a dependent variable, such that all scores fall at the low end of their possible distribution
What is a history threat?
a threat to internal variability that occurs when it is unclear whether a change in the treatment group is caused by the treatment itself or by an external or historical factor that affects most members of the group
What is an instrumentation threat?
a threat to internal validity that occurs when a measuring instrument changes over time
What is maturation threat?
a threat to internal validity that occurs when an observed change in an experimental group could have emerged more ore less spontaneously over time
What is a masked design?
a study design in which the observers are unaware of the experimental conditions to which participants have been assigned
What is a manipulation check?
in an experiment, an extra dependent variable researchers can include to determine how well a manipulation worked
What is a measurement error?
the degree to which the recorded measure for a participant on some variable differs from the true value of the variable for that participant
What is a null effect?
a finding that an independent variable did not make a difference in the dependent variable; there is no difference, no relationship, or no effect in a population
What is noise?
unsystematic variability among the members of a group in an experiment, which might be caused by situation noise, individual differences, or measurement error
What is one-group, pretest/posttest design?
An experiment in which a researcher recruits one group of participants; measures them on a pretest ; exposes them to a treatment , intervention, or change ; and then measures then on a posttest
What is power?
the likelihood that a study will show a significant result when an independent variable truly has an effect in the population, the probability of not making a type 2 error
What is a regression threat?
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 measure (with or without the experimental treatment)
What is regression to the mean?
A phenomenon in which an extreme finding is likely to be closer to its own typical, or mean, level the next time is is measure, because the same combination of chance factors that made he finding extreme are not present the second time
What is selection-history threat?
a threat to internal validity in which a historical or seasonal event systematically affects only the participants in the treatment group or only those in the comparison group, not both
What is selection attrition threat?
a threat to internal validity in which participants are likely to drop out of either the treatment group or the comparison group, not both
What is situation noise?
unrelated events or distractions in the external environment that creates unsystematic variability within groups in an experiment
What is testing threat?
In a repeated-measures experiment or quasi-experiment, a kind of order effect in which scores change over time just because participants have taken the test more then once; includes practice effects
