What is an additive relationship?The control variable is a cause of the dependent variable but it only defines a small compositional difference across X; Z is only an auxiliary, ''additional'' component of the the independent variable X.

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What is assignment at random?Random assignment of subjects to experimental and control groups.
What is a case study design?A comprehensive and in-depth study of a single case or several cases. A non-experimental design in which the investigator has little control over events.
What is a classical experimental design?An experiment with the random assignment of subjects to experimental and control groups with a pre-test and post-test for both groups.


What is a cohort?A group of people who all experience a significant event in roughly the same time frame.
What is a compositional difference?any quality that changes across the categories of an independent variable (ex: Gender represents a compositional difference in the support of gun control between Democrats and Republicans)

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What is a control group?A group of subjects who do not receive the experimental treatment or test stimulus.

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What is a controlled comparison?A comparison accomplished by examining the relationship between and independent and a dependent variable, while holding constant other variables suggested by rival explanations and hypotheses.

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What are demand characteristics?Aspects of the research situation that cause participants to guess the purpose or rationale of the study and adjust their behavior or opinions accordingly.
What is a deviant case study?Study of a case that deviates from other cases and from what prevailing theory would lead the researcher to expect.
What is an experimental design?framework that ensures that the test and control groups of an experiment are identical in every way except for the independent variable

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What is an experimental effect?Effect, usually measured numerically, of the independent variable on the dependent variable.


What is a experimental group?A group of subjects who receive the experimental treatment or test stimulus.
What is experimental mortality?A differential loss of subjects from experimental and control groups that affects the equivalency of groups; threat to internal validity.
What is experimentation?A research design in which the researcher controls exposure to the test factor or independent variable, the assignment of subjects to groups, and the measurement of responses.
Define external validity.The ability to generalize from one set of research findings to other situations.

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What are extraneous factors?Factors besides the independent variable that may cause change in the dependent variable.
What is a factorial design?Experimental design used to measure the effect of two or more independent variables singly and in combination.
What is a field experiment?Experimental designs applied in a natural setting.

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What is a formal model?A simplified and abstract representation of reality that can be expressed verbally, mathematically, or in some other symbolic system, and that purports to show how variables or parts of a system are interconnected.


What are history effects?A change in the dependent variable due to changes in the environment over time; threat to internal validity.
What is Instrument Decay?A change in the measurement device used to measure the dependent variable, producing change in measurements; threat to internal validity.
What is instrument reactivity?Reaction of subjects to a pre-test.
What is an interaction relationship?The relationship between X and Y depends on the value of Z; oftentimes, line representations of the data will show an intersection of the two lines for Z.

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What is internal validity?The ability to show that manipulation or variation of the independent variable actually causes the dependent variable to change.

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What is an intervention analysis?Also known as interrupted time series design. A non-experimental design in which the impact of a naturally occurring event (intervention) on a dependent variable is measured over time.
What is a laboratory experiment?In a laboratory experiment, the control group and the test group are studied in an environment created wholly by the investigator.

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What is Maturation effect?A change in subjects over time that affects the dependent variable; threat to internal validity.


What is a Multi-group Design?Experimental design with more than one control and experimental group.
What is a Non-experimental Design?A research design characterized by at least one of the following: presence of a single group, lack of researcher control over the assignment of subjects to control and experimental groups, lack of researcher control over application of the independent variable, or inability of the researcher to measure the dependent variable before and after exposure to the independent variable occurs.
What are observational studies?In social science research, many studies observe the outcomes for available subjects on variables without any experimental manipulation of the subjects.
What is Panel Mortality?Loss of participants from a panel study.


What is a Period Effect?An indicator or measure of history effects on a dependent variable during a specified time period.
What is a post-test?Measurement of the dependent variable after manipulation of the independent variable.
What is precision matching?matching of pairs of subjects with one of the pair assigned to the experimental group and the other to the control group.
What is a pre-test?measurement of the dependent variable prior to the administration of the experimental treatment or manipulation of the independent variable.


What is random assignment?The random assignment of subjects to the experimental and control groups.

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What is a repeated measurement design?An experimental design in which the dependent variable is measured at multiple times after the treatment is administered.
What is a research design?A plan specifying how the researcher intends to fulfill the goals of the study; a logical plan for testing hypotheses.

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What is a rival explanation?a cause for variation the dependent variable that is an alternative to the hypothesized explanation

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Define selection bias.Bias in the assignment of subjects to the experimental and control groups; threat to internal validity.

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What is a simple post-test design?Weak type of experimental design with control and experimental groups but no pre-test.
What is a simulation?A simple representation of a system by a device in order to study its behavior.
What is a small-N design?Type of experimental design in which one ro a few cases of a phenomenon are examined in considerable detail, typically using several data collection methods, such as personal interviews, document analysis, and observation.


What is a spurious relationship?A relationship between two variables caused entirely by the impact of a third variable.

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What is statistical regression?Change in the dependent variable due to the temporary nature of extreme values; threat to internal validity.
What is survey research?The direct or indirect solicitation of information from individuals by asking them questions, having them fill out forms, or using other means.
What is a test group?a group of subjects receiving treatment

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What is a test stimulus (test factor)?The independent variable introduced and controlled by an investigator in order to assess its effects on a response or dependent variable.
What are testing effects?Effect of a pre-test on the dependent variable; threat to internal validity.
What is a time series design?A research design featuring multiple measurements of the dependent variable before and after experimental treatment.