Term
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Definition
| the loss of participants during a study |
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Term
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Definition
| the portion of the total variance in a set of scores that reflects systematic differences between the experimental groups |
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Term
| between-subjects/groups design |
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Definition
| an experimental design in which each participant serves in only one condition of the experiment |
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Term
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Definition
| a threat to internal validity that occurs when participants are assigned to conditions in a nonrandom manner, producing systematic differences among conditions prior to introduction of the independent variable |
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Term
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Definition
| effects that may occur in a within-subjects experiment when the effect of a particular level of the independent variable persists even after the treatment ends; carryover effects may lead researchers to conclude that a particular level of the independent variable had an effect on participants' responses when the effect was actually caused by a level that was administered earlier |
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Term
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Definition
| one level of an independent variable |
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Term
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Definition
| an accomplice of an experimenter whom participants assume to be another participant or an uninvolved bystander |
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Term
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Definition
| a condition that exists in experimental research when something other than the independent variable differs systematically among the experimental conditions |
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Term
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Definition
| the portion of the total variance in a set of scores that is due to extraneous variables that differ systematically between the experimental groups |
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Definition
| participants in an experiment who receive a zero level of the independent variable |
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Term
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Definition
| a procedure used in within-subjects design in which different participants receive the levels of the independent variable in different orders; counterbalancing is used to avoid systematic order effects |
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Term
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Definition
| aspects of a study that indicate to participants how they are expected to respond |
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Term
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Definition
| the response measured in a study, typically a measure of participants' thoughts, feelings, behavior, or physiological reactions |
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Term
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Definition
| the loss of participants during a study in a manner such that the loss is not randomly distributed across conditions |
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Term
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Definition
| the practice of concealing the purpose and hypotheses of a study both from the participants and from the researchers who have direct contact with the participants |
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Term
| environmental manipulation |
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Definition
| an independent variable that involves the experimental modification of the participant's physical or social environment |
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Term
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Definition
| that portion of the total variance in a set of data that remains unaccounted for after systematic variance is removed; variance that is unrelated tot he variables under investigation in a study |
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Term
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Definition
| research in which the researcher assigns participants to conditions and manipulates at least one independent variable |
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Term
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Definition
| the practice of eliminating or holding constant extraneous variables that might affect the outcome of an experiment |
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Term
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Definition
| participants in an experiment who receive a nonzero level of the independent variable |
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Term
| experimenter expectancy effect |
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Definition
| situation in which a researcher's expectations about the outcome of a study influence participants' reactions (Rosenthal effect) |
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Term
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Definition
| situation in which, generally speaking, the greater the internal validity of an experiment, the lower its external validity, and vice versa |
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Term
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Definition
| the degree to which the results obtained in one study can be replicated or generalized to other samples, research settings, and procedures |
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Term
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Definition
| effects that may occur in a within-subjects experiment when participants' performance declines during the study because they become tired, bored or unmotivated as they serve in more than one experimental condition; fatigue effects may lead researchers to conclude that participants' poor performance in a particular experimental condition was due to the independent variable when it was actually due to fatigue, disinterest, or lack of motivation |
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Term
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Definition
| changes in participants' responses between pretest and posttest that are due to an outside, extraneous influence rather than to the independent variable |
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Term
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Definition
| in an experiment, the variable that is varied or manipulated by the researcher to assess its effects on participants' behavior |
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Term
| instructional manipulation |
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Definition
| an independent variable that is varied through verbal information that is provided to participants |
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Term
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Definition
| the degree to which a researcher draws accurate conclusions about the effects of an independent variable |
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Definition
| an independent variable that directly alters the participant's body, such as surgical procedures, or the administration of chemical substances |
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Definition
| an experimental design used to control for order effects in a within-subjects design |
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Term
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Definition
| one value of an independent variable |
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Term
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Definition
| a measure designed to determine whether participants in an experiment perceived different levels of the independent variable differently |
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Term
| matched random assignment |
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Definition
| a procedure for assigning participants to experimental conditions in which participants are first matched into homogeneous blocks and then participants within each block are assigned randomly to conditions |
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Term
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Definition
| changes in participants' responses between pretest and posttest that are due to the passage of time rather than to the independent variable; aging, fatigue, and hunger may produce maturation effects |
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Term
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Definition
| effects that may occur in a within-subjects experiment when participants' responses are affected by the order in which they receive various levels of the independent variable; order effects may lead researchers to conclude that a particular level of the independent variable had an effect when, in fact, the effect was produced by administering the levels of the independent variable in a particular order |
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Term
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Definition
| a preliminary study that examines the usefulness of manipulations or measures that later will be used in an experiment |
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Term
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Definition
| participants who receive an ineffective treatment; this is used to identify and control for placebo effects |
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Term
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Definition
| a physiological or psychological change that occurs as a result of the mere suggestion that the change will occur |
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Term
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Definition
| the degree to which a research design is sensitive to the effects of the independent variable; powerful designs are able to detect effects of the independent variable more easily than less powerful designs |
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Term
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Definition
| effects that may occur in a within-subjects experiment when participants' performance improves merely because they complete the dependent variable more than once; practice effects may lead researchers to conclude that participants' performance was due to the independent variable when it was actually caused by completing the dependent variable multiple times |
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Term
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Definition
| the situation that occurs when completing a pretest affects participants' responses on the posttest |
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Term
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Definition
| that portion of the total variance in a set of scores that is due tot he independent variable; treatment variance |
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Term
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Definition
| an experimental design in which each participant serves in only one condition of the experiment |
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Term
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Definition
| an experimental design in which each participant serves in more than one condition of the experiment |
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Term
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Definition
| variance in a set of scores that is due to systematic differences between the experimental groups that are not due to the independent variable; confound variance |
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Term
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Definition
| effects that may occur in a within-subjects experiment when participants become aware of the purpose of the experiment as they serve in more than one experimental condition; sensitization effects may lead researchers to conclude that participants' performance was due to the independent variable when it was actually caused by serving in multiple conditions of the experiment |
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Term
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Definition
| placing participants in experimental conditions in such a way that every participant has an equal chance of being selected from the population |
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Term
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Definition
| a personal characteristic of research participants, such as age, gender, self-esteem, or extraversion |
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Term
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Definition
| the portion of the total variance in a set of scores that is related in an orderly, predictable fashion to the variables the researcher is investigating |
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Term
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Definition
| that portion of the total variance in a set of scores that is due to the independent variable; primary variance |
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Term
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Definition
| research that is conducted using the web |
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Term
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Definition
| the variability among scores within a particular experimental condition |
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Term
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Definition
| an experimental design in which each participant serves in more than one condition of the experiment; repeated measures design |
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Term
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Definition
| an experimental design that combines one or more between-subjects factors with one or more within-subjects factors; also called mixed factorial, split-plot design |
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Term
| expericorr factorial design |
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Definition
| an experimental design that includes one or more manipulated independent variables and one or more preexisting participant variables that are measured rather than manipulated; also called mixed factorial design |
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Term
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Definition
| creating two groups of participants that have unusually low or unusually high scores on a particular variable |
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Term
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Definition
1. in experimental designs, an independent variable
2. in factor analysis, the underlying dimension that is assumed to account for observed relationships among variables |
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Term
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Definition
| an experimental design in which two or more independent variables are manipulated |
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Term
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Definition
| the combined effect of two or more independent variables such that the effect of one independent variable differs across the levels of the other independent variable(s) |
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Term
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Definition
| the effect of a particular independent variable, ignoring the effects of other independent variables in the experiment |
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Term
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Definition
| an experimental design in which participants are matched into homogeneous blocks, and participants in each block are randomly assigned to the experimental conditions |
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Term
| matched-subjects factorial design |
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Definition
| an experimental design involving two or more independent variables in which participants are first matched into homogeneous blocks and then, within each block, are randomly assigned to the experimental conditions |
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Term
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Definition
| assigning participants to two groups depending on whether their scores on a particular variable fall above or below the median of the variable |
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Term
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Definition
1. an experimental design that includes one or more between-subjects factors and one or more within-subjects factors; also called between-within design
2. also refers to an experiemntal design that includes both manipulated independent variables and measured participant variables; also called expericorr design |
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Term
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Definition
| a variable that qualifies or moderates the effects of another variable on behavior |
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Term
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Definition
| an experimental design with a single independent variable |
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Term
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Definition
| an experiment in which participants' responses are measured only once - after introduction of the independent variable |
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Term
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Definition
| an experiment in which participants' responses are measured twice - once before and once after introduction of the independent variable |
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Term
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Definition
| the situation that occurs when completing a pretest affects participants' responses on the posttest |
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Term
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Definition
| an experimental design in which each participant serves in only one condition of the experiment; also called between-groups or between-subjects design |
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Term
| randomized groups factorial design |
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Definition
| an experimental design involving two or more independent variables in which each participant serves in only one condition of the experiment |
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Term
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Definition
| an experimental design in which each participant serves in more than one condition of the experiment; a within-subjects design |
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Term
| repeated measures factorial design |
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Definition
| an experimental design involving two or more independent variables in which each participant serves in all conditions of the experiment |
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Term
| split-plot factorial design |
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Definition
| a factorial design that combines one or more between-subjects factors with one or more within-subjects factors; also called mixed-factorial design and between-within design |
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Term
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Definition
| a personal characteristic of research participants, such as age, gender, self-esteem, or extraversion |
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Term
| two-group experimental design |
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Definition
| an experiment with two conditions; the simplest possible experiment |
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Term
| coefficient of determination |
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Definition
| the square of the correlation coefficient; indicates the proportion of variance in one variable that can be accounted for by the other variable |
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Term
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Definition
| research designed to examine the nature of the relationship between two measured variables |
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Term
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Definition
| an index of the direction and magnitude of the relationship between two variables; the value of a correlation coefficient ranges from -1.00 to +1.00 |
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Term
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Definition
| an inverse relationship between two variables such that participants with high scores on one variable tend to have low scores on the other variable, and vice versa |
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Term
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Definition
| an extreme score; typically scores that fall father than 3 standard deviations from the mean are considered outliers |
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Term
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Definition
| the correlation between two variables with the influence of one or more other variables removed |
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Term
| Pearson correlation coefficient |
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Definition
| the most commonly used measure of correlation |
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Term
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Definition
| a correlation of -2.00 or +1.00, indicating that two variables are so closely related that one can be perfectly predicted from the other |
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Term
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Definition
| a statistic that expresses the correlation between two dichotomous variables |
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Term
| point biserial correlation |
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Definition
| the correlation between a dichotomous and a continuous variable |
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Term
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Definition
| a direct relationship between two variables such that participants with high scores on one variable tend also to have high scores on the other variable, whereas low scorers on one variable tend also to score low on the other |
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Term
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Definition
| a set of data in which participants' scores are confined to a narrow range of the possible scores |
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Term
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Definition
| a graphical representation of participants' scores on two variables; the values of one variable are plotted on the x-axis and those of the other variable are plotted on the y-axis |
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Term
| Spearman rank-order correlation |
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Definition
| a correlation coefficient calculated on variables that are measured on an ordinal scale |
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Term
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Definition
| a finding that is very unlikely to be due to error variance |
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Term
| comparative time series design |
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Definition
| a quasi-experimental design that examines two or more variables over time to understand how changes in one variable are related to changes in another variable; also called comparative trend analysis |
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Term
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Definition
| a threat to the internal validity of a quasi-experiment that develops when another event occurs at the same time as the quasi-independent variable |
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Term
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Definition
| the philosophy that researchers should use many ways of obtaining evidence regarding a particular hypothesis rather than relying on a single approach |
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Term
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Definition
| a survey design in which a group of respondents is studied once |
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Term
| experimental contamination |
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Definition
| a situation that occurs when participants in one experimental condition are indirectly affected by the independent variable in another experimental condition because they interacted with participants in the other condition |
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Term
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Definition
| differences among people of various ages that are due to the different conditions under which each generation has grown up rather than age differences |
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Term
| interrupted time series design with a reversal |
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Definition
| a study in which (1) the dependent variable is measured several times; (2) the independent variable is introduced; (3) the dependent variable is measured several more times; (4) the independent variable is then withdrawn; and (5) the dependent variable is again measured several times |
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Term
| interrupted time series design with multiple replications |
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Definition
| a study in which (1) the dependent variable is measured several times; (2) the independent variable is introduced; (3) the dependent variable is measured again; (4) the independent varaible is withdrawn; (5) the dependent variable is measured; (6) the independent variable is introduced a second time; (7) more measures of the dependent variable are taken; (8) the independent variable is once again withdrawn; and (9) the dependent variable is measured after the independent variable has been withdrawn for the second time |
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Term
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Definition
| a threat to internal validity in which an extraneous event happens to one experimental group that does not happen to the other groups |
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Term
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Definition
| a study in which a single group of participants is studied over time |
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Term
| nonequivalent control group design |
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Definition
| a quasi-experimental design in which the group of participants that receives the quasi-independent variable is compared to one or more groups of participants who do not receive the treatment |
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Term
| nonequivalent groups posttest-only design |
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Definition
| a quasi-experimental design in which two preexisting groups are studied - one that has received the quasi-independent variable and one that has not |
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Term
| nonequivalent groups pretest-posttest design |
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Definition
| a quasi-experimental design in which two preexisting groups are tested - one that has received the quasi-independent variable and one that has not; each group is tested twice - once before and once after one group receives the quasi-independent variable |
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Term
| one-group pretest-posttest design |
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Definition
| a preexperimental design in which one group of participants is tested before and after a quasi-independent variable has occurred; because it fails to control for nearly all threats to internal validity, this design should never be used |
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Term
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Definition
| a design that lacks the necessary controls to minimize threats to internal validity; typically preexperimental designs do not involve adequate control or comparison groups |
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Term
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Definition
| the use of behavioral research methods to assess the effects of programs on behavior; also called evaluation research |
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Term
| quasi-experimental design |
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Definition
| a research design in which the researcher cannot assign participants to conditions and/or manipulate the independent variable; instead comparisons are made between groups that already exist or within a single group before and after a quasi-experimental treatment has occurred |
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Term
| quasi-independent variable |
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Definition
| the independent variable in a quasi-experimental design; the designator quasi-independent is used when the variable is not manipulated by the researcher |
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Term
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Definition
| the tendency for participants who are selected on the basis of their extreme scores on some measure to obtain less extreme scores when they are retested |
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Term
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Definition
| a threat to internal validity that arises when the experimental groups were not equivalent before the manipulation of the independent or quasi-independent variable |
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Term
| selection-by-history interaction |
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Definition
| a threat to internal validity in which an extraneous event happens to one experimental group that does not happen to the other groups |
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Term
| simple interrupted time series design |
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Definition
| a quasi-experimental design in which participants are tested on many occasions-several before and several after the occurrence of the quasi-independent variable |
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Term
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Definition
| a class of quasi-experimental designs in which participants are tested on many occasions-several before and several after the occurrence of a quasi-independent variable |
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