| predictive value | An expresion of the likelihood that a given test result correlates with the presence or absence of disease. A positive predictive value is the ratio of patients with the disease who test positive to the entire population of individuals with a positive test result; a negative predictive value is the ratio of patients without the disease who test negative to the entire population of individuals with a negative test. (05 Mar 2000) |
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| predictive value of tests | In screening and diagnostic tests, the probability that a person with a positive test is a true positive (i.e., has the disease), is referred to as the predictive value of a positive test; whereas, the predictive value of a negative test is the probability that the person with a negative test does not have the disease. Predictive value is related to the sensitivity and specificity of the test. (12 Dec 1998) |
| heating value | The maximum amount of energy that is available from burning a substance. (05 Dec 1998) |
| Hehner value | The weight or percentage of the nonvolatile fatty acids yielded by 5 g of a saponified fat or oil. Synonym: Hehner value. (05 Mar 2000) |
| higher heating value | (HHV) The maximum potential energy in dry fuel. For wood, the range is 7,600 to 9,600 Btu/lb. (05 Dec 1998) |
| homing value | In a cybernetic system such as homeostasis, that value of a trait of interest that the restorative forces are directed towards maintaining. (05 Mar 2000) |
| soil value | The relative lightness or intensity of colour, approximately a function of the square root of the total amount of light, one of the three variables of colour. (09 Oct 1997) |
| nutritive value | An indication of the contribution of a food to the nutrient content of the diet. This value depends on the quantity of a food which is digested and absorbed and the amounts of the essential nutrients (protein, fat, carbohydrate, minerals, vitamins) which it contains. This value can be affected by soil and growing conditions, handling and storage, and processing. (12 Dec 1998) |
| S value | Svedberg Unit. See: sedimentation coefficient. (18 Nov 1997) |
| iodine value | An indication of the quantity of unsaturated fatty acids present in a fat; it represents the number of grams of iodine absorbed by each 100 g of fat. See: hydrogen number. Synonym: iodine value. (05 Mar 2000) |
| tenth-value layer | <radiobiology> Thickness of a specified substance which, when introduced into the path of a given beam of radiation, reduces the absorbed dose index or dose-equivalent index to one-tenth. The magnitude of the tenth-value layer may be different for absorbed dose index and dose equivalent index. (16 Dec 1997) |
| thiocyanogen value | The number of grams of thiocyanogen taken up by 100 g of fat; analogous to the iodine number, except that thiocyanogen will not add to all the double bonds in polyunsaturated fatty acids as will iodine. Synonym: thiocyanogen value. (05 Mar 2000) |
| threshold limit value | The maximum concentration of a chemical recommended by the American Conference of Government Industrial Hygienists for repeated exposure without adverse health effects on workers. (05 Mar 2000) |
| economic value of life | The evaluation of the monetary value of a life lost or a life saved. (12 Dec 1998) |
| law of initial value | The direction of response of a body function to any agent depends to a large degree on the initial level of that function. Synonym: law of initial value. (05 Mar 2000) |