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| a threat to the internal validity of a study; occurs when participants fail to complete a study, usually but not necessarily in longitudinal studies; those finishing the study may not be equivalent to those who started it |
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| any experimental design in which different groups of participants serve in the different conditions of the study |
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| any statistical analysis investigating the relationship between two variables |
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| a procedure used to accomplish random assignment and ensure an equal number of participants in each condition; ensure that each condition of the study has a subject randomly assigned to it before any coondition has a sunject assigned to it again; also used in within-subjects design as a counter-balancing procedure to ensure that when participants are tested in each condition more than once, they experience each condition once before experiencing any condition again |
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| form a sequence of effect in which systematic changes in performance occur as a result of completing one sequence of conditions rather than a different sequence |
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| occurs when scores on two or more conditions are at or near the maximun possible for the scale being used, giving the impression that no differences exist between the conditions |
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| coefficient of determination (r^2) |
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| for two correlated factors, the proportion of variance in one factor than can be atriubuted to the second factor; found by squaring Pearson's r |
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| a cohort in a group of people born at about the same time; cohort effects can reduce the internal validity of cross-sectional studies because differences between groups could result from the effects of growing up in different historical eras |
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| in developmental psychology research, a design that combines cross-sectional and longitudinal designs; a new cohort is added to a study every few years, and then studied periodically throughout the time course of the study |
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| complete counterbalancing |
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| occurs when all possible orders of conditions are used in a within-subects design |
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| statistical conclusion validity |
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| said to exist when the researcher uses statistical asalysis properly and draws the appropriate conclusions from the analysis |
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| any extraneous variable that covaries with the independent variable and could provide an alternative explanation for the results |
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| in measurement, it occurs when the measure being used accuratley assesses some hypothetical construct; also refers to whether the contruct itself is valid; in research, refers to whether the operational definitions used for independent and dependent variables are valid |
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| a group not given a treatment that is being evaluated in a study; provides a means of comparison |
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| a table that summarizes a series of correlations among several variables |
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| for a within-subjects variable, any procedure designed to control for sequence effects |
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| form of validity in which a psychological measure is able to predict some future behavior or is meaningfully related to some other measure |
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| in a regression analysis, this is the variable that is being predicted from the predictor varible (e.g., college grades are predicted from SAT scores) |
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| cross-lagged panel correlation |
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| refers to a type of correlational research designed to deal with the directionality problem; if variables X and Y are measured at two different times and if X precedes Y, then X might cause Y but Y cannot cause X |
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| In developmental psychology, a design in which age is the indepentdent variable and different groups of people are tested; each group is of a different age |
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| any feature of the experimental design or procedure that increases the chances that participants will detect the true purpose of the study |
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| behavior measured as the outcome of an experiment |
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| In correlational research, this refers to the fact that for a correlation between variables X and Y, it is possible that X is causing Y, but it is also possible that Y is causing X; the correlation alone provides no basis for deciding between the two alternatives |
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| a control procedure designed to reduce bias; neither the participant nor the person conducting the experimental session knows which condition of the study is being tested; often used in studies evaluation drug effects |
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| said to exist when research studies psychological phenomena in everyday situations (e.g., memory for where we put our keys) |
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| groups of participants in a between-subjects design that are essentially equal to each other in all ways except for the different levels of the independent variable |
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| a form of anxiety experienced by participants that leads them to behave so as to be evaluated positively by the experimenter |
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| a research procedure in which some factor is varied, all else is held constant, and some result is measured |
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| in a study with an indentified control group, the experimental group is given the treatment being tested |
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| occurs when an experimenter's expectations about a study affects its outcome |
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| the extent to which the findings of a study generalize to other populations. other settings, and other times |
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| any uncontrolled factor that is not of interest to the researcher but could affect the results |
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| a multivariate analysis in which a large number of variables are intercorrelated; variables that correlate highly with each other form "factors." |
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| an experiment that is conducted outside the laboratory; a narrower term than field research |
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| research that occurs in any location other than a scientific laboratory |
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| occurs when scores on two of more conditions are at or near the mininum possible for the scale being used, giving the impression that no differences exist between the conditions |
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| a form of participants bias in which participants try to guess the experimenter's hypothesis and then behave in such a way as to confirm it |
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| name often given to a form of participant bias in which behavior is influenced by the mere knowledge that the participant is in an experiment and is therefore of some importance to the experimenter |
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| a threat to internal validity of a study; occurs when some historical event that could addect participants happens between the beginning of a study and its end |
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| the factor of interest to the researcher; it can be directly manipulated by the experimenter, or participants can be selected by virtue of their possesing certain attributes |
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| type of independent variable in which participants are given different sets of instructions about how to perform (e.g. given a list of stimuli, various groups might be told to process them in different ways) |
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| the extent to which a study is free from methodological flaws, especially confounding factors |
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| a form of correlation used when pairs of scores do not come from the same individual, as when correlations are calculated for pairs of twins |
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| form of partial counterbalancing in which each condition of the study occurs equally often in each sequential position and each condition procedes and follows each other condition exactly one time |
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| in developmental psychology, a design in which age is the independent variable and the same group of people are teted repeatedly at different ages |
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| in debriefing, a procedure to determine if subjects were aware of a deception experiment's true purpose; also refers to any procedure that determines if systematic manipulations have intedned effect on participants |
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| a procedure for creating equivalent groups in which participants are measured on some factor (a "matching variable") expected to correlate with the dependent variale; groups are then formed by taking participants who score at the same level on the matching variable and randomly assigning them to groups |
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| any variable selected for matching participants in a matched groups study |
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| a threat to the internal validity of a study; occurs when participants change from the beginning to the end of the study simply as a result of maturational changes within them and not as a resultof some independent variable |
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| a multivariate analysis that includes a criterion variable and two or more predictor variables; the predictors will have different weights |
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| any statistical analysis investigating the relationship among more than two variables |
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| a relationship between varuales X and Y such that a high score for X is associated with a low score for Y and a low score for X is associated with a high score for Y |
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| a multivariate statistical procedure for evaluating the effects of third varibles; if the correlation between X and Y remains high, even after some third factor Z has been "partialed out," then Z can be eliminated as a third variable |
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| occurs when a subset of all possible orders of conditions is used in a within-subjects design (e.g., a random sample of the population of all possible orders could be selected). |
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| can occur when the behavior of participants is influenced by their beliefs about how they are supposed to behave in a study |
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| measure of the size of a correlation between two variables; ranges from a perfect postitive correlation of +1.00 to a perfect negative correlation of -1.00; if r=0l, then no relationship exists between the variables |
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| a relationship between variables X and Y such that a high score for X is associated with a high score for Y and a low score for X is associated with a low score for Y |
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| a measurement given to participants at the conclusion of a study after they have experienced a treatment or been in a control group; comparisons are made with pretest scores to determine if change occured |
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| in a regression analysis, the variable used to predict the criterion variable (e.g., SAT scores are used to predict college grades). |
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| a measurement given to participants at the outset of a study, prior to their being given a treatment (or not treated, when particiants are in a control group) |
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| in a within-sujects design, any sequence effect in which the accumulated effects are assumed to be the same from trial to trial (e.g., fatigue) |
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| a detailed description of the sequence of events in a research session; used by an experimenter to ensure uniformity of treatment of research participants |
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| one of experimental psychology's original areas of research; investigatesthe relationshop between physical stimuli and the perception of those stimuli; studies threshold |
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| in correlational research, knowing the size of the correlation and a value for variable X, it is possible to predict a value for variable Y; this process occurs through a regression analysis |
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| summarizes the points of a scatterplot and provides the means for making predictions |
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| if a score on a test is extremely high or low, a second score taken will be closer to the mean score; can be a threat to the internal validity of a study if a pretest score is extreme and the posttest score changes in the direction of the mean |
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| another name for a within-subjects design; participants are tested in each of the experiments conditions |
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| occurs in a correlational study when on a limited range of scores for one or both of the variables is usedl range restrictions tend to lower correlations |
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| occurs in a within-subjects design when participants are tested more than once per condition; subjects experience one sequence, and then a second with the order reversed from the first (e.g., A-B-C-C-B-A) |
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| a graph depicting the relationship shown by a correlation |
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| sequence or order effects |
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| can occur in a within-subjects design when the experience of participating in one of the conditions of the study influences performance in subsequence conditions (see progressive effect and carryover effect) |
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| type of independent variable in which subjects encounter different environmental circumstances (e.g., large vs. small rooms in a crowding study). |
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| a form of reliability in which one-half of the items (e.g., the even numbered items) on a test are correlated with the remaining items |
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| group of students asked to participate in research, typically as part of an introductory psychology course requirement; sometimes called a "participant pool." |
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| subject selection effects |
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| a threat to the internal validity of a study; occurs when those participating in a study cannot be assigned randomly to groups; hence the groups are nonequivalent |
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| a type of independent variable that is selected rather than manipulated by the experimenter; refers to an already existing attribute of the individuals chosen for the study (e.g., gender) |
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| type of independent variable in which participants are given different types of tasks to perform (e.g., mazes that differ in level of difficulty) |
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| a form of reliability in whcih a test is administered on two seperate occasions and the correlation between them is calculated |
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| a threat to the internal validity of a study; occurs when the factof taking a pretest influences posttest scores, perhaps by sensitizing participants to the purpose of a study |
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| refers to the problem of drawing causal conclusions in correlational research; third variables are any uncontrolled factors that cound underline a correlation between variables X and Y. |
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| any experimental design in which the same participants serve in each of the different conditions of the study; also called a "repeated-measures design" |
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