experimental design

experimental design

[eksper′imen′təl]

Etymology: L, experimentum + designare, to mark out

(in research) a study design used to test cause-and-effect relationships between variables. The classic experimental design specifies an experimental group and a control group. The independent variable is administered to the experimental group and not to the control group, and both groups are measured on the same dependent variable. Subsequent experimental designs have used more groups and more measurements over longer periods. True experiments must have control, randomization, and manipulation.

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design [de-zīn´]

a strategy that directs a researcher in planning and implementing a study in a way that is most likely to achieve the intended goal.

case study design an investigation strategy involving extensive exploration of a single unit of study, which may be a person, family, group, community, or institution, or a very small number of subjects who are examined intensively. The number of variables is usually very large.

cohort design longitudinal design.

cross-sectional design a research strategy in which one or more group(s) of subjects are studied at one given point in time.

experimental design a research design that eliminates all factors that influence outcome except for the cause being studied (independent variable). All other factors are controlled by randomization, investigator-controlled manipulation of the independent variable, and control of the study situation by the investigator, including the use of control groups.

longitudinal design a research strategy in which one or more group(s) of subjects in various stages of development are examined simultaneously with the intent of inferring trends over time. The assumption is that the phenomenon under study progresses with time. Called also cohort design.

methodological design a process used to develop the validity and reliability of instruments to measure constructs used as variables in research.

nonequivalent control group design a study design in which the control group is not selected by random means.

partial correlation design a design developed to eliminate the influence of a third variable on a relational pattern by holding it constant mathematically, so that the magnitude of the relationship between the two remaining variables can be determined.

path analysis design a design to determine the accuracy of a theoretical model: a hypothesized causal model is developed from the theoretical model and the major variables within it are measured and relationships among them determined; regression analysis is used to determine whether the data are consistent with the model.

survey design a design in which data are collected with questionnaires or through personal interviews with members of an identified population.

time dimensional design an investigation strategy for the examination of sequence and patterns of change, growth, or trends across time; see also prospective study and retrospective study.

trend design a research strategy to examine changes in the general population in relation to a particular phenomenon by means of data collected at predetermined intervals of time from different samples selected from the general population.

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experimental

emanating from or pertaining to experiment.

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experimental animals

animals kept expressly for the purposes of conducting experiments on them. Called also laboratory animals.

experimental design

the method of allocating experimental units to treatment groups in an experiment; many complicated and sophisticated designs are available, e.g. balanced, unbalanced, crossover, factorial, randomized, non-random, split-plot.

experimental epidemiology

the study of changes effected in populations by changes made in the factors affecting their performance, behavior or health.

experimental model

experiment carried out using a model of a real system which contains some of the risk factors which apply in the real state; the model is a simplification of real life.

experimental study

a study in which all of the risk factors are under the direct control of the investigator.