control group

control group

n.

A group used as a standard of comparison in a control experiment.

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control group,

a set of items or people that serves as a standard or reference for comparison with an experimental group. A control group is similar to the experimental group in number and is identical in specified characteristics, such as sex, age, annual income, parity, or other factors, but does not receive the experimental treatment or intervention.

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control group,

n in a clinical trial, the group of subjects that does not receive the active treatment. Having a control group allows comparisons by factoring out confounding variables so that any remaining differences may be attributed to the variable (i.e., the active treatment).

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control group,

n the group of participants in a clinical study who do not receive the drug or treatment being studied against which the reactions of individuals in the experimental group may be compared. See also controlled clinical trial.

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control

1. the governing or limitation of certain objects or events.

2. a standard against which experimental observations may be evaluated, as a procedure identical to the experimental procedure except for the one factor being studied; a requirement of any planned experimental study. Also, any individual of the group exhibiting the standard characteristics.

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disease control

restraining or reducing the prevalence of individual disease. Includes the range of strategies from limitation of occurrence to eradication. Implies legislative control of notifiable disease.

control elements

nucleotide sequences on DNA that usually precede (upstream) the sequences coding for the structural gene at which regulator proteins act.

control factor

in a comparison between diseases caused by a number of contributing factors it may be necessary to supply controls for one or more of these factors.

control group

the group of animals with which the experimental group is to be matched; the group which has not had its variables manipulated experimentally. The selection of the animals to be included in the two groups may be based on matching them with respect to age, to their history of nutrition or inheritance, or vaccination or prophylactic treatment. Called also controls.

ovulation control

prevention of ovulation by administration of progesterone or stimulation of ovulation by injection of follicle-stimulating hormone are examples.

paired control

comparison between the experimental and control groups is most accurate if the control animal for each experimental animal is selected to be as similar as possible, i.e. a paired control.

control pole

a pole with a noose at the end used to catch and restrain small animals.

control population

a large control group.

population control

a variety of techniques are used with contraception being least used. Permanent surgical interference is common in food, racing and companion animal groups, and termination of pregnancy and estrus synchronization, both by hormonal means, are also extensively practiced. Increasing the culling rate is the standard procedure for dealing with a feed shortage.

x-ray control unit

the controlling mechanisms in an x-ray machine. Include the voltmeter and voltage compensator control, the kilovoltage, milliameter and milliamperage selectors and the timer and exposure control button.