(sam'pĕl )

[Fr. esample, example fr. L. exemplum]

1. A piece or portion of a whole that demonstrates the characteristics or quality of the whole, e.g., a specimen of blood.
2. In research, a portion of a population selected to represent the entire population.

   SEE: specimen.

biased s.In epidemiology or medical research, a sample of a group that does not equally represent the members of the group.

convenience s.A group of research subjects selected casually, without scrupulously rand omizing them, usually because they are easily accessible to the researcher.

fasting blood s.A laboratory specimen obtained after the patient has abstained from eating for a minimum of 8 hr.

Fasting samples are used to gauge lipid levels and blood sugar, e.g., in the diagnosis and evaluation of diabetes mellitus or hypercholesterolemia.

fetal blood s.A small amount of blood drawn from a fetal scalp vein to assess acid-base status. The normal fetal blood pH level is 7.25. Levels between 7.20 and 7.24 reflect a preacidotic state; levels below 7.20 indicate acidosis and fetal jeopardy.

grab s.In public health and medical statistics, a chaotic set of data from which conclusions are carelessly drawn. Because the sample is not carefully rand omized or scientifically selected, the conclusions derived from such sample groups may be inaccurate.

judgment s.A research cohort whose members are chosen because they share a common set of qualities. Because of the selection criteria used in assembling the group, the judgment sample is not rand om, and the conclusions drawn from research on such a sample do not have broad applicability to the larger community.

quota s.A cohort of research subjects selected because a certain percentage of them has a desired characteristic.

rand om s.In experimental medicine and epidemiology, an unbiased selection of individuals or items. A rand om sample is chosen in research investigations so that study results will have a high probability of reflecting the variables under study rather than unintentionally reflecting an unanticipated characteristic of the research subjects.

snowball s.A group of research subjects who help, through word of mouth or casual contact, to select other research subjects.

spiked s.A neutral (negative) test reagent to which a specific antigen or chemical has been added. It is used to assess the reliability of clinical laboratory testing.

wipe s.A technique to identify the presence of an allergen, pathogen, or toxin by rubbing a wet cloth on a surface and analyzing the materials it picks up.