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| all the individuals to whom a research project is meant to generalize |
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| a small percentage of the target population |
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| involves systematically assigning numbers to objects, events, or characteristics according to a set of rules |
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| classifies objects or individuals as belonging to different categories (the order of the categories is arbitrary and unimportant) |
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| differs from a nominal scale in that the order of the categories is important |
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| characterized by equal unites of measurement throughout the scale (do not have a true zero value) |
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| provides information about order; all units are of equal size throughout the scale and there is a true zero value |
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| procedures that organize, summerize and describe a set of data |
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| the score that occurs most frequently |
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| two scores that tie for occuring most frequently |
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| three or more scores that tie for occuring most frequently |
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| the middle point in a set of scores |
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| the arithmatic average of the scores in a distribution |
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| scores that are inordinately large or small compared to the other scores |
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| measures of central tendency |
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| the degree to which scores are close to the average or are spread out |
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| number of possible values for scores in a descrete data set or the number of intervals of scores covered by a data set taken from a continuous distribution (highest score - lowest score + 1) |
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| average distance that the scores in a set of data will fall from the mean |
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| the standard deviation squared |
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| a measure of the degree of relationship between two variables |
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| when an increase in one variable is accompanied by an increase in the other variable |
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| an increase in one variable is accompanied by a decrease in the other variable |
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| used to demonstrate the relationship between two variables by plotting dots on a graph |
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| the variation among scores that is not caused by the independent variable but instead is caused by random factors or by extraneous variables |
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| an inferential statistical test for comparing two means |
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| analysis of variance (ANOVA) |
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| an inferential statistical test for comparing the means of three or more groups |
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| an estimate of the effect of the independent variable plus error variance |
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| a statistical test that does not require as many assumptions about the population represented by the sample as does a parametric test (also called assumption-free test or assumption-freer test) |
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| a characteristic of a population |
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| statistical test in which the sample statistics are assumed to be estimates of population parameters |
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| investigations in which the researcher manipulates an independent variable to see if there are any differences in the dependent variable among equivilant groups of participants |
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| an investigation in which relationships between or among variables can be identified, but causual inferences cannot be made because of the possible effects of uncontrolled variables |
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| an innert treatment that has no effect on the dependent variable |
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| between-groups research design |
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| a research design in which the performance of participants in two or more groups is compared |
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| assinging participants to experimental conditions within an investigation in a manner such that each participant is equally likely to be assigned to each condition |
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| the confound arising when there are differences between the comparison groups within a study |
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| identifying pairs (or triplets, quadruplets and so on)of participants who measure similarily on a characteristic that is related to the dependent variable and then randomly assigning each of these participants to seperate experimental conditions |
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| typically used to look at differences between difffent age groups |
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| variables other than the independent variable that can effect the dependent variable |
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| results in an investigation that can be explained in various ways because of the presence of one or more extraneous variables |
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| the extent to which the design of an experiment ensures that the independent variable, and not some other variable or variables, caused the measured difference to the dependent variable |
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| an extraneous variable or other flaws in the research design that yield alternative explanations for the results and thus limit the studies internal validity |
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| when the researchers expectations effect the outcome of a study (a confounding variable) |
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| ques inadvertantly provided by the researcher, the research materials, or the research setting that supply the research participant with information about the purpose of the investigation |
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| participants do not know which experimental condition they are in or the experimenter does not know |
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| neither the experiment nor the participants are aware of the experimental conditions to which particular participants have been assigned |
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| occurs when the instrument used to measure the dependent variable changes in accuracy over time |
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| subject mortality (or subject attrition) |
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Definition
| the loss of data when participants withdraw from a study, or their data cannot be used. |
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| nonsystematic subject mortality |
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Definition
| the loss of data when particpants withdraw from a study or their data cannot be used for reasons unrelated to the experiment itself. |
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| systematic subject mortality |
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Definition
| the loss of data occurig when more participants from one experimental condition withdraw from a study than another (the participants who quit are distributed unevenly among the various groups |
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| comparable treatment of groups |
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| a necessary condition for conducting research using a between-groups design |
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| sensitivity of the dependent variable |
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| the ability of the dependent variable to demonstrate subtle differences between the experimental conditions |
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Definition
| the situation in which the dependent variablt yeilds scores at or near the top limit of the measurement tool for one or all of the conditions |
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| dependent variable yeilds scores near the lower limit of the measurement tool for one or all groups |
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| a technique in which each participant experiences condition A followed by B and condition B followed by A |
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| a complete within-subjects design that involves the random presentation of blocks of conditions; each block is composed of single presentations of each experimental condition |
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| in a within-subjects design, the result obtained when one experimental condition affects performance in another condition |
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| complete within-subjects design |
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Definition
| a research design in which each participant experiences each experimental condition several times, until he or she has received all possible orders of the conditions |
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Definition
| a procedure for distributing the effect of an extraneous variable across the experimental conditions within a within-subjects design |
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Definition
| cues inadvertently provided by the researcher, the research materials, or the research setting that supply the research participant with information about the purpose of the investigation |
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Definition
| the confound arising when participants' performance on a task declines becauses they have repeated the task |
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Definition
| a change in participants' performance on the dependent measure due to an event that occurs during the course of the investigation |
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| incomplete within-subjects design |
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Definition
| a research design in which each participant receives a unique order of the conditions and may receive each condition more than once, but does not receive all possible orderings of the conditions |
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Definition
| a technique for an incomplete within-subjects design in which each condition is presented in each ordinal position and is presented before and after each other condition. The number of sequences necessary is equal to the number of cinditions in the study; thus, writing one sequence on each line, we obtain a square. The four conditions for this are: ABCD, BDAC, CADB, DCBA |
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Definition
| a repeated-measures design meant to look for changes that occur over time |
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| a chcange in the participants' performance on the dependent variable due simply to the passage of time |
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| the confound arising when participants' performance on a task improves because they ahve repeated the task |
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| measureements made in a nonequivalent-control-group design before and after the introduction of a treatment to the experimental group |
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| random order with rotation |
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Definition
| a technique for presenting conditions to participants in an incomplee within-subjects design. In this approach, the experimental conditions are ordered randomly and the first subject receives this order. Another order of the conditions is obtained by moving the first condition to the last place and shifting all of the other conditions up one; the next subject receives this order. Then the conditions are moved one place forward again, and thee previously first condition is shifted to last place; the next subject receives this order. This rotation continues until each condition has occupied each position in the sequence. |
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| regression toward the mean |
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Definition
| the phenomenon that extreme scores tend to be less extreme upon retesting; they move toward the mean |
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Definition
| a reaseach design in which one group of subjects is tested two or more times by means of the same measurement tool |
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| the phenomenon in which repeated testing leads to better scores |
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| a research design in which each participant receives each level of the independent variable at least once |
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| the type of design in which two or more independent variables on a dependent variable is assessed. Several hypotheses are tested. |
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Definition
| the effect of an independent variable on dependent measure |
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| a smaller preliminary study conducted to answer questions about procedures for the full scale version of the investigation |
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| an important technique for presenting the results of a factorial design so that they can be more easily interpreted. |
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Definition
| the average scores for each level of an independent variable, disregarding other independent variables. Marginal means are used in factorial designs to interpret main effects. |
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| mixed design (split pilot design) |
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Definition
| a factorial design involving at least one between-groups and one within-subjects variable |
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| factorial designs that involve more than one independent variable |
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