Nutrition Test #1

Experimental group

the people or animals participating in an experiment who receive the treatment under investigation. Also called experimental subjects. See also control group and intervention studies.

Control Group

A group of individuals who are similar in all possible respects to the group being treated in an experiment but who receive a sham treatment instead of the real one. Also called control subjects. See also experimental group and intervention studies.

Blind Experiment

An experiment in which the subjects do not know whether they are members of the experimental group or the control group. In a double-blind experiment, neither the subjects nor the researchers know to which group the members belong until the end of the experiment.

Correlation

The simultaneous change of two factors, such as the increase of weight with increasing height (a direct or positive correlation) or the decrease of cancer incidence with increasing fiber intake (an inverse or negative correlation). A correlation between two factors suggests that one may cause the other but does not rule out the possibility that both may be caused by chance or by a third factor.

Placebo

a sham treatment often used in scientific studies; and inert harmless medication. The placebo effect is the healing effect that the act of treatment, rather than the treatment itself, often has.

Case Studies

studies of individuals. In clinical settings, researchers can observe treatments and their apparent effects. To prove that a treatment has produced an effect requires simultaneous observation of an untreated similar subject (a case control).

Intervention Studies

studies of populations in which observation is accomanied by experimental manipulation of some population members-for example, a study in which half the subjects (the experimental subjects) follow diet advice to reduce fat intakes while the other half (the contrl subjects) do not, and both groups' heart health is monitored.

Epidemiological studies

studies of populations; often used in nutrition to search for correlations between dietary habits and disease incidence; a first step in seeking nutrition-related causes of diseases.

Laboratory studies

studies that are performed under tightly controlled conditions and are designed to pinpoint causes and effects. Such studies often use animals as subjects