KAP (KNOWLEDGE, ATTITUDES, PRACTICE) SURVEY A formal survey, using face- to-face interviews, in which people are asked standardized pretested questions dealing with their knowledge of, attitudes toward, and use of contraceptive methods. Detailed reproductive histories and attitudes toward desired family size are also elicited. Anal- ysis of responses provides much useful information on family planning and gives estimates of possible future trends in population structure. The term has sometimes been used to describe other varieties of surveys of knowledge, attitudes, and practice (e.g., health promotion in general or, in particular, cigarette smoking).

KAPLAN-MEIER ESTIMATE (Syn: product-limit method) A nonparametric method of estimating survival probabilities from life tables.267 This combines calculated probabili- ties of survival and estimates to allow for censored observations, which are assumed to occur randomly. The intervals are defined as ending each time an event (death, with- drawal) occurs; they may therefore be unequal.

KAPPA A measure of the degree of nonrandom agreement between observers or measurements of the same categorical variable

PP κ=0e

1 − Pe

where P0 is the proportion of times the measurements agree and Pe is the proportion of times they can be expected to agree by chance alone. If the measurements agree more often than expected by chance, kappa is positive; if concordance is complete, kappa = 1; if there is no more nor less than chance concordance, kappa = 0; if the measurements disagree more than expected by chance, kappa is negative.

KENDALL’S TAU See correlation coefficient.
KNOWLEDGE CONSTRUCTION A production-oriented approach to the understand-

ing of science. Analyses of how knowledge is created identify strategies that scientists employ in their work, discursive fact production, features of fact construction shared across contemporary sciences and epistemic communities, devices of representation, laboratory cultures, object reconfiguration in the laboratory, knowledge cultures and their “epistemic machineries” (i.e., their machineries of knowledge production), or social mechanisms of consensus formation. Interest in the process of knowledge production has led to an improved understanding of science as a practical accomplishment.268 See also sociology of scientific knowledge.

KOCH’S POSTULATES See Henle-Koch postulates. See also causality; Evans’s postulates.

KRIGING A method first used in the earth sciences to smooth data from spatially scat- tered point measurements (e.g., drill sites). It is used in geographic epidemiology.269 The method relies on analysis of the spatial variability of the data and allows represen- tation of the variable under study as a continuous process throughout the country. The method is named for its developer, D. G. Krige.

KURTOSIS The extent to which a unimodal distribution is peaked.