| genetic variance | Within a population, the measure of how much of the variation of a particular phenotype is due to genotypic variation (as opposed to environmental factors. An example might be the height of a human as determined by genes inherited from the human's parents. See: environmental variance. (09 Oct 1997) |
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| analysis of variance | A statistical technique that isolates and assesses the contributions of categorical independent variables to variation in the mean of a continuous dependent variable. (12 Dec 1998) |
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| ball variance | Swelling and changes in shape and consistency of the ball in a ball-valve prosthesis, especially in one replacing the aortic valve. (05 Mar 2000) |
| variance | 1. The state of being variable, different, divergent, or deviate; a degree of deviation. 2. A measure of the variation shown by a set of observations, defined as the sum of squares of deviations from the mean, divided by the number of degrees of freedom in the set of observations. (05 Mar 2000) |
| variance ratio | The distribution of the ratio of two independent estimates of the same variance from a gaussian distribution based on samples of sizes (n + 1) and (m + 1) respectively. Estimates are usually based on one such sample analyzed in such a way as to make them independent e.g., analysis of variance; and F may be used to test a null hypothesis that the observed differences among sample means is no greater than could readily be accounted for by chance. (05 Mar 2000) |
| environmental variance | Within a population, the measure of how much of the variation of a particular phenotype is due to environmental factors (as opposed to variations in genotype. An example might be the height of a human as determined by such factors as nutrition or infectious diseases during childhood. See: genetic variance. (09 Oct 1997) |
| ulnar variance | <radiology> Ulna minus variance ulna shorter than radius increased frequency of avascular necrosis of lunate associated with DISI, ulna plus variance ulna longer than radius increased stress on triangular fibrocartilage (12 Dec 1998) |
| genetic | <biology> Pertaining to reproduction or to birth or origin. (07 May 1998) |
| genetic amplification | A process for producing an increase in pertinent genetic material, particularly for increasing the proportion of plasmid DNA to that of bacterial DNA. Includes the production of extrachromosomal copies of the genes for RNA. (05 Mar 2000) |
| genetic assimilation | <genetics> A situation in which a characteristic that is normally expressed only in certain environmental situations becomes fixed in a population so that it no longer requires environmental factors to be expressed. (07 May 1998) |
| genetic association | The occurrence together in a population, more often than can be readily explained by chance, of two or more traits of which at least one is known to be genetic. (05 Mar 2000) |
| genetic block | <biochemistry, molecular biology> An obstruction in a biochemical pathway caused by a mutation that has crippled production of an enzyme critical to the pathway. (07 May 1998) |
| genetic burden | The genetic debt due to harmful mutation but as yet undischarged. (In a large population of fixed size every mutation with diminished genetic fitness will eventually become extinct and depending on the details of inheritance and phenotype must be paid for by a fixed number of genetic deaths per mutation, the genetic debt.) (05 Mar 2000) |
| genetic carrier | An unaffected heterozygote bearing a usually harmful recessive gene, a cancer that bears a dominant but latent age-dependent trait to have offspring with unbalanced karyotypes. (05 Mar 2000) |
| genetic code | <molecular biology> Relationship between the sequence of bases in nucleic acid and the order of amino acids in the polypeptide synthesised from it. A sequence of three nucleic acid bases (a triplet) acts as a codeword (codon) for one amino acid. (18 Nov 1997) |
| genetic colonisation | <molecular biology> The process of a parasite (such as a virus) inserting genes into a host's genome which cause the host cell to synthesise products that are only useful to the parasite. (07 May 1998) |