Ch 9: Intro to Simple Experiments Flashcards
between-subjects designs
an experimental design in which different groups pf participants are exposed to different levels of the independent variable such that each participant experiences only one level of the independent variable
carryover effects
a threat to internal validity that occurs when being exposed to one condition changes how people react to a later condition
concurrent-measures designs
an experiment using a within-groups design in which participants are exposed to all the levels of an independent variable at roughly the same time, and a single attitudinal or behavioral preference is the dependent variable
condition
one of the levels of the independent variable in an experiment
confounds
a potential alternative explanation for a research finding (a threat to internal validity)
control group
a level of an independent variable that is intended to represent “no treatment” or a neutral condition
control variable
a potential variable that an experimenter holds constant on purpose
counterbalancing
presenting the levels of the independent variable to participants in different orders to control for order effects
demand characteristics
cues that lead participants to guess a study’s hypotheses or goals
dependent variable
in an experiment, the variable that is measured, or the outcome variable
design confound
a second variable that happens to vary systematically along with the independent variable and therefore is an alternative explanation for the results
independent variable
a variable that is manipulated in an experiment
independent-groups design
an experimental design in which different groups pf participants are exposed to different levels of the independent variable such that each participant experiences only one level of the independent variable
Latin square
a formal system of partial counterbalancing that ensures that each condition appears in each condition at least once
manipulation checks
an extra dependent variable that researchers can include in an experiment to determine how well an experimental manipulation worked
matched-groups design
an experimental design in which participants who are similar on some measured variable are grouped into sets and the members of each matched set are then randomly assigned to different experimental conditions
order effects
a threat to internal validity that occurs when being exposed to one condition changes how people react to a later condition
partial counterbalancing
a method of counterbalancing in which some, but not all, of the possible condition orders are represented
pilot study
a study completed before (or sometimes after) the study of primary interest, usually to test the effectiveness or characteristics of the manipulations
placebo group
a control group that is exposed to an inert treatment (ex: sugar pill)
posttest-only design
an experiment with an independent groups design in which participants are tested on the dependent variable only once
power
the probability that a study will show a statistically significant result when some effect is truly present in the population
practice effects
a type of order effect in which people’s performance improves over time because they become practiced at the dependent measure (not because of the manipulation or treatment)
pretest/posttest design
an experiment with an independent-groups design in which participants are tested on the key dependent variable twice- once before and once after exposure to the independent variable
random assignment
the use of a random method (ex: flipping a coin) to assign participants into different experimental groups)
repeated-measures design
an experiment with a within-groups design in which participants respond to a dependent variable more than once, after exposure to each level of the independent variable
selection effect
a threat to internal validity that occurs when the kinds of participants at one level of the independent variable are systematically different from those at the other level of the independent variable
systematic variability
in an experiment, the situation that occurs when the levels of a variable coincide in some predictable way with experimental group membership, creating a potential confound
treatment group
the participants in an experiment who are exposed to the level of the independent variable that involves a drug, therapy, or intervention
unsystematic variability
in an experiment, the levels of a variable occurring independently of experimental group membership, contributing to variability within groups
within-groups design
a study design in which each participant is presented with all levels of the independent variable
