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Definition
| All circumstances that occur or exist before the event or behavior to be explained; also called antecedents. |
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Definition
| Research that is designed to solve real-world problems. |
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Definition
| Research designed to test theories or to explain psychological phenomena. |
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| Cause-and-effect relationship |
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Definition
| The relation between a particular behavior and a set of antecedents that always precedes it—whereas other antecedents do not—so that the set is inferred to cause the behavior. |
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Definition
| Everyday, nonscientific collection of psychological data used to understand the social world and guide our behavior. |
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Definition
| Facts and figures gathered from observations in research. (Data is the plural form of the Latin word datum, so to be correct we say that data are gathered rather than that data is gathered.) |
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| Data that are observable or experienced; capable of being verified or disproved through investigation. |
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| The process undertaken to demonstrate that particular behavioral events will occur reliably in certain specifiable conditions; a principal tool of the scientific method. |
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| Organized and rational thought, characterized by open-mindedness, objectivity, and parsimony; a principal tool of the scientific method. |
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| General scientific principles that explain our universe and predict events. |
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| The systematic estimation of the quantity, size, or quality of an observable event; a principal tool of the scientific method. |
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| The scientific techniques used to collect and evaluate psychological data. |
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| The systematic noting and recording of events; a principal tool of the scientific method. |
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| An aspect of good thinking, stating that the simplest explanation is preferred until ruled out by conflicting evidence; also known as Occam’s razor. |
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| A field of study that gives the appearance of being scientific but has no true scientific basis and has not been confirmed using the tools of the scientific method: observation, measurement, and experimentation. |
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Definition
| A controlled procedure in which at least two different treatment conditions are applied to subjects whose behaviors are then measured and compared to test a hypothesis about the effects of the treatments on behavior. |
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| The process of repeating research procedures to verify that the outcome will be the same as before; a principal tool of the scientific method. |
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Definition
| The systematic gathering of data to provide descriptions of events taking place under specific conditions, enabling researchers to explain, predict, and control events. |
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| Steps scientists take to gather and verify information, answer questions, explain relationships, and communicate findings. |
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Definition
| The scientific term for an individual who participates in research. |
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Definition
| Capable of being tested; typically used in reference to a hypothesis. Three requirements must be met to have a testable hypothesis: procedures for manipulating the setting must exist, and the predicted outcome must be observable and measurable. |
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Definition
| A set of general principles that attempts to explain and predict behavior or other phenomena. |
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| A specific set of antecedent conditions created by the experimenter and presented to subjects to test its effect on behavior. |
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| The degree to which scores on the measuring instrument correlate with another known standard for measuring the variable being studied. |
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Definition
| An error that occurs when the value of an extraneous variable changes systematically along with the independent variable in an experiment; an alternative explanation for the findings that threatens internal validity. |
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Definition
| The degree to which an operational definition accurately represents the construct it is intended to manipulate or measure. |
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| `The degree to which the content of a measure reflects the content of what is being measured. |
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Definition
| The specific behavior that a researcher tries to explain in an experiment; the variable that is measured. |
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| Experimental operational definition |
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Definition
| The explanation of the meaning of independent variables; defines exactly what was done to create the various treatment conditions of the experiment. |
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Definition
| A variable other than an independent or dependent variable; a variable that is not the focus of an experiment but can produce effects on the dependent variable if not controlled. |
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Definition
| The degree to which a manipulation or measurement technique is self-evident. |
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Definition
| A threat to internal validity in which an outside event or occurrence might have produced effects on the dependent variable. |
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Definition
| Concepts used to explain unseen processes, such as hunger, intelligence, or learning; postulated to explain observable behavior. |
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| Independent variable (IV) |
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Definition
| The variable (antecedent condition) that the experimenter intentionally manipulates. |
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Definition
| A threat to internal validity produced by changes in the measuring instrument itself. |
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Definition
| The degree to which different items measuring the same variable attain consistent results. |
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Definition
| The certainty that the changes in behavior observed across treatment conditions in the experiment were actually caused by the independent variable. |
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Definition
| The degree of agreement among different observers or raters. |
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Definition
| The type of scale of measurement—either ratio, interval, ordinal, or nominal—used to measure a variable. |
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Term
| Levels of the independent variable |
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Definition
| The two or more values of the independent variable manipulated by the experimenter. |
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Definition
| An assessment to determine whether the independent variable was manipulated successfully. |
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Definition
| A threat to internal validity produced by internal (physical or psychological) changes in subjects. |
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| Measured operational definition |
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Definition
| The description of exactly how a variable in an experiment is measured. |
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Definition
| The section of a research report in which the subjects and experiment are described in enough detail that the experiment may be replicated by others; it is typically divided into subsections, such as Participants, Apparatus or Materials, and Procedures. |
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Definition
| The specification of the precise meaning of a variable within an experiment; defines a variable in terms of observable operations, procedures, and measurements. |
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Definition
| The degree to which a measuring instrument yields information allowing prediction of actual behavior or performance. |
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Definition
| The consistency and dependability of experimental procedures and measurements. |
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Definition
| A family of threats to internal validity produced when a selection threat combines with one or more of the other threats to internal validity; when a selection threat is already present, other threats can affect some experimental groups but not others. |
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Definition
| A threat to internal validity that can occur when nonrandom procedures are used to assign subjects to conditions or when random assignment fails to balance out differences among subjects across the different conditions of the experiment. |
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Term
| Statistical regression threat |
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Definition
| A threat to internal validity that can occur when subjects are assigned to conditions on the basis of extreme scores on a test; upon retest, the scores of extreme scorers tend to regress toward the mean even without any treatment. |
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Definition
| A threat to internal validity produced by differences in dropout rates across the conditions of the experiment. |
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Definition
| Consistency between an individual’s scores on the same test taken at two or more different times. |
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Definition
| A threat to internal validity produced by a previous administration of the same test or other measure. |
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Definition
| The soundness of an operational definition; in experiments, the principle of actually studying the variables intended to be manipulated or measured. |
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Definition
| A technique used to control the impact of extraneous variables by distributing their effects equally across treatment conditions. |
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Definition
| A control procedure used to avoid confounding; keeping all aspects of the treatment conditions identical except for the independent variable that is being manipulated. |
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Definition
| Extraneous variable stemming from procedures created by the environment, or context, of the research setting. |
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Definition
| A plausible but false explanation of the procedures in an experiment told to disguise the actual research hypothesis so that subjects will not guess what it is. |
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Definition
| The aspects of the experimental situation itself that demand or elicit particular behaviors; can lead to distorted data by compelling subjects to produce responses that conform to what subjects believe is expected of them in the experiment. |
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Definition
| An experiment in which neither the experimenter nor the subjects know which treatment condition the subjects are in; used to control experimenter bias. |
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Definition
| A technique to control extraneous variables by removing them from an experiment. |
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Definition
| Any behavior of the experimenter that can create confounding in an experiment. |
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Definition
| The personal characteristics that an experimenter or volunteer subject brings to the experimental setting. |
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Definition
| Aspects of the testing conditions that need to be controlled. |
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Definition
| The result of giving subjects a pill, injection, or other treatment that actually contains none of the independent variable; the treatment elicits a change in subjects’ behavior simply because subjects expect an effect to occur. |
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Definition
| The phenomenon of experimenters treating subjects differently depending on what they expect from the subjects; also called the Pygmalion effect. |
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Definition
| An experiment in which subjects are not told which of the treatment conditions they are in; a procedure used to control demand characteristics. |
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Definition
| The qualities of the relationships between subjects and experimenters that can influence the results of an experiment. |
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Definition
| A statement that is always true. |
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Definition
| A statement that is always false. |
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Definition
| The process of reasoning from general principles to specific instances; most useful for testing the principles of a theory. |
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Definition
| Concluding section of the research report, used to integrate the experimental findings into the existing body of knowledge, showing how the current research advances knowledge, increases generalizability of known effects, or contradicts past findings. |
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Definition
| A statement that is a tentative explanation of an event or behavior; it predicts the effects of specified antecedent conditions on a measured behavior. |
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Definition
| A statement that is worded so that it is falsifiable, or disprovable, by experimental results. |
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Definition
| A statement that leads to new studies. |
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Definition
| The thesis, or main idea, of an experiment or study consisting of a statement that predicts the relationship between at least two variables. |
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Definition
| The process of reasoning from specific cases to more general principles to form a hypothesis. |
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Definition
| Beginning section of a research report that guides the reader toward your research hypothesis; includes a selective review of relevant, recent research. |
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Definition
| The development of ideas from hunches; knowing directly without reasoning from objective data. |
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Definition
| A statistical reviewing procedure that uses data from many similar studies to summarize and quantify research findings about individual topics. |
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| Nonexperimental hypothesis |
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Definition
| A statement of predictions of how events, traits, or behaviors might be related, but not a statement about cause and effect. |
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Definition
| A statement that is simple and does not require many supporting assumptions. |
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Definition
| A periodical that publishes individual research reports and integrative research reviews, which are up-to-date summaries of what is known about a specific topic. |
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Definition
| The knack of finding things that are not being sought. |
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Definition
| A statement that can be either true or false, a condition necessary to form an experimental hypothesis. |
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Definition
| A statement that can be tested because the means exist for manipulating antecedent conditions and for measuring the resulting behavior. |
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Definition
| The grouping together and averaging of data gathered in various ways, including aggregation over subjects, over stimuli and/or situations, over trials and/or occasions, and over measures. |
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Definition
| An experiment conducted outside the laboratory that is used to increase external validity, verify earlier laboratory findings, and investigate problems that cannot be studied successfully in the laboratory. |
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Definition
| An assessment to determine whether the independent variable was manipulated successfully. |
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Term
| Multivariate analysis of variance (MANOVA) |
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Definition
| The statistical procedure used to study the impact of independent variables on two or more dependent variables; an extension of analysis of variance. |
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Definition
| Research design or statistical procedure used to evaluate the effects of many dependent variables in combination, including multiple correlation, factor analysis, and multivariate analysis of variance. |
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Definition
| A descriptive, nonexperimental method of observing behaviors as they occur spontaneously in natural settings. |
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Definition
| The tendency of subjects to alter their responses or behaviors when they are aware of the presence of an observer. |
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| Statistical conclusion validity |
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Definition
| The degree to which conclusions about a treatment effect can be drawn from the statistical results obtained. |
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Definition
| A procedure used to assess subjects’ behaviors without their knowledge; used to obtain more nonreactive data. |
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Definition
| A brief summary of the report (approximately 150–250 words), which precedes the four major sections. |
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Definition
| The fourth major section of the research report, used to draw conclusions and to integrate the experimental findings into the existing body of knowledge. |
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Term
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Definition
| Beginning section of a research report that guides the reader toward your research hypothesis; includes a selective review of relevant, recent research. |
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Definition
| The section of a research report in which the subjects and experiment are described in enough detail that the experiment may be replicated by others; it is typically divided into subsections, such as Participants, Stimuli or Materials, and Procedures. |
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Definition
| A list of books and articles cited in the research report; placed at the end of the report. |
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Definition
| Written report of psychological research, which contains four major sections: Introduction, Method, Results, and Discussion. |
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Definition
| The section of a research report in which the findings are described and the results of statistical tests and summary data are presented. |
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Definition
| A short version of the title, which will appear as a header at the top of pages of the published report. |
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Definition
| A concise, impersonal, and unbiased form of writing used in research reports. |
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Definition
| The name of the report, which describes what the report is about; typically includes the variables tested and the relationship between them. |
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Definition
| A statement that the data came from different populations; the research hypothesis, which cannot be tested directly. |
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Definition
| Portion in the tail(s) of the distribution of a test statistic extreme enough to satisfy the researcher’s criterion for rejecting the null hypothesis—for instance, the most extreme 5% of a distribution where p , .05 is the chosen significance level. |
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Definition
| The standard procedures used to summarize and describe data quickly and clearly; summary statistics reported for an experiment, including mean, range, and standard deviation. |
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Definition
| A statement that predicts the exact pattern of results that will be observed, such as which treatment group will perform best. |
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Definition
| Variation in subjects’ scores produced by uncontrolled extraneous variables in the experimental procedure, experimenter bias, or other influences on subjects not related to effects of the independent variable. |
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Definition
| Statistics that can be used as indicators of what is going on in a population; also called test statistics. |
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Definition
| An arithmetical average computed by dividing the sum of a group of scores by the total number of scores; a measure of central tendency. |
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Term
| Measures of central tendency |
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Definition
| Summary statistics that describe what is typical of a distribution of scores; include mean, median, and mode. |
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Term
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Definition
| The score that divides a distribution in half, so that half the scores in the distribution fall above the median, half below; a measure of central tendency. |
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Definition
| The most frequently occurring score in a distribution; a measure of central tendency. |
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Term
| Nondirectional hypothesis |
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Definition
| A statement that predicts a difference between treatment groups without predicting the exact pattern of results. |
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Term
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Definition
| The distribution of data in a symmetrical, bell-shaped curve. |
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Definition
| A statement that the performance of treatment groups is so similar that the groups must belong to the same population; a way of saying that the experimental manipulation had no important effect. |
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Definition
| A statistical procedure used when a directional prediction has been made; the critical region of the distribution of the test statistic is measured in just one tail of the distribution. |
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Definition
| The difference between the largest and smallest scores in a set of data; a rough indication of the amount of variability in the data. |
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Definition
| Data recorded as an experiment is run; the responses of individual subjects. |
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Definition
| The statistical criterion for deciding whether to reject the null hypothesis or not, typically p , .05. |
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Term
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Definition
| The square root of the variance; measures the average deviation of scores about the mean, thus reflecting the amount of variability in the data. |
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Term
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Definition
| A statement made about a population and all its samples based on the samples observed. |
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Definition
| Meeting the set criterion for significance; the data do not support the null hypothesis, confirming a difference between the groups that occurred as a result of the experiment. |
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Definition
| Quantitative measurements of samples; quantitative data. |
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Definition
| Descriptive statistics computed from the raw data of an experiment, including the measures of central tendency and variability. |
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Definition
| Statistics that can be used as indicators of what is going on in a population and can be used to evaluate results; also called inferential statistics. |
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Definition
| A statistical procedure used when a nondirectional prediction has been made; the critical region of the distribution of the test statistic is divided over both tails of the distribution. |
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Definition
| An error made by rejecting the null hypothesis even though it is really true; stating that an effect exists when it really does not. |
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Term
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Definition
| An error made by failing to reject the null hypothesis even though it is really false; failing to detect a treatment effect. |
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Definition
| Fluctuation in data; can be defined numerically as the range, variance, or standard deviation. |
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Term
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Definition
| The average squared deviation of scores from their mean; a more precise measure of variability than the range. |
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Term
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Definition
| Statistical test between specific treatment groups that was anticipated, or planned, before the experiment was conducted; also called planned comparison. |
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Term
| Analysis of variance (ANOVA) |
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Definition
| The statistical procedure used to evaluate differences among three or more treatment means by breaking the variability in the data into components that reflect the influence of error and error plus treatment effects. |
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Term
| Between-groups variability |
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Definition
| The degree to which the scores of different treatment groups differ from one another (that is, how much subjects vary under different levels of the independent variable); a measure of variability produced by treatment effects and error. |
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Term
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Definition
| A nonparametric, inferential statistic that tests whether the frequencies of responses in our sample represent certain frequencies in the population; used with nominal data. |
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Term
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Definition
| A range of values above and below a sample mean that is likely to contain the population mean with the probability level (usually at 95% or 99%) that the mean of the population (the true mean) would actually fall somewhere in that range. |
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Definition
| The value of the test statistic that must be exceeded to reject the null hypothesis at the chosen significance level. |
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Term
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Definition
| The number of members of a set of data that can vary or change value without changing the value of a known statistic for those data. |
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Term
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Definition
| The variability within and between treatment groups that is not produced by changes in the independent variables; variability produced by individual differences, experimental error, and other extraneous variables. |
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Term
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Definition
| A test statistic used in the analysis of variance; the ratio between the variability observed between treatment groups and the variability observed within treatment groups. |
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Term
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Definition
| An average squared deviation; a variance estimate used in analysis-of-variance procedures and found by dividing the sum of squares by the degrees of freedom. |
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Term
| Mean square between groups (MSb) |
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Definition
| The variance (or average squared deviation) across different treatment groups produced by error and treatment effects; found by dividing the sums of squares by the degrees of freedom. |
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Term
| Mean square within groups (MSw) |
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Definition
| The variance (or average squared deviation) within a single treatment group; produced by the combination of sources called error. |
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Term
| One-way between-subjects analysis of variance |
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Definition
| Statistical procedure used to evaluate a between-subjects experiment with three or more levels of a single independent variable. |
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Term
| One-way within-subjects (or repeated measures) ANOVA |
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Definition
| Statistical procedure used to evaluate a within-subjects experiment with three or more levels of a single independent variable. |
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Term
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Definition
| Statistical test performed after the overall analysis indicates a significant difference; used to pinpoint which differences are significant. |
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Term
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Definition
| A term describing a statistical test that can be used without increasing the probability of Type 1 or Type 2 errors even though its assumptions (e.g., the population is normally distributed and has equal variances) are violated. |
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Term
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Definition
| A statistic that relates differences between treatment means to the amount of variability expected between any two samples of data from the same population; used to analyze the results of a two-group experiment with one independent variable and interval or ratio data. |
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Term
| t test for independent groups |
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Definition
| A statistic that relates differences between treatment means to the amount of variability expected between any two samples of data from the same population; used to analyze the results of a two-group experiment with independent groups of subjects. |
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Term
| t test for matched groups |
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Definition
| A statistic that relates differences between treatment means to the amount of variability expected between any two samples of data from the same population; used to analyze two-group experiments using matched-subjects or within-subjects designs. Also called a within-subjects t test. |
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Term
| Within-groups variability |
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Definition
| The degree to which the scores of subjects in the same treatment group differ from one another (that is, how much subjects vary from others in the group); an index of the degree of fluctuation among scores that is attributable to error. |
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