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induction, in logic

(Encyclopedia)induction, in logic, a form of argument in which the premises give grounds for the conclusion but do not necessitate it. Induction is contrasted with deduction, in which true premises do necessitate t...

chorionic villus sampling

(Encyclopedia)chorionic villus sampling (CVS) or chorionic villus biopsy (CVB) kōrˌē-ŏnˈĭk, kôrˌ– [key], diagnostic procedure in which a sample of chorionic villi from the developing placenta is removed f...

school vouchers

(Encyclopedia)school vouchers, government grants aimed at improving education for the children of low-income families by providing school tuition that can be used at public or private schools. The idea behind schoo...

programmed instruction

(Encyclopedia)programmed instruction, method of presenting new subject matter to students in a graded sequence of controlled steps. Students work through the programmed material by themselves at their own speed and...

Agent Orange

(Encyclopedia)Agent Orange, herbicide used by U.S. forces during the Vietnam War to expose enemy guerrilla forces in forested areas. Agent Orange contains varying amounts of dioxin. Exposure to the defoliant has be...

Bush, George Walker

(Encyclopedia)Bush, George Walker, 1946–, 43d President of the United States (2001–9), b. New Haven, Conn. The eldest son of President George H. W. Bush, he was was raised in Texas and, like his father, attende...

Grateful Dead, The

(Encyclopedia)Grateful Dead, The, American rock music group formed in 1965 by guitarists Jerry Garcia, 1942–95, and Bob Weir, 1947–, harmonica player Ron “Pigpen” McKernan, 1945–73, bassist Phil Lesh, 194...

econometrics

(Encyclopedia)econometrics, technique of economic analysis that expresses economic theory in terms of mathematical relationships and then tests it empirically through statistical research. Econometrics attempts to ...

phosphate

(Encyclopedia)phosphate, salt or ester of phosphoric acid, H3PO4. Because phosphoric acid is tribasic (having three replaceable hydrogen atoms), it forms monophosphate, diphosphate, and triphosphate salts in which ...

Rotblat, Sir Joseph

(Encyclopedia)Rotblat, Sir Joseph, 1908–2005, British physicist and anti-nuclear weapons activist, b. Warsaw, Poland; grad. Free Univ. of Poland (M.A., 1932), Univ. of Warsaw (Ph.D., 1938), Univ. of Liverpool (Ph...