| distribution function | <radiobiology> Function characterising the density of particles located at a given point in phase space (a combination of velocity and/or position coordinates) at a given time. The velocity-space distribution function gives the number of particles with a particular velocity, the position-space distribution function is synonymous with the particle density in position-space. Different combinations of position and spatial coordinates are useful in different problems. (09 Oct 1997) |
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| distribution leukocytosis | An abnormally large proportion of one or more types of leukocytes. (05 Mar 2000) |
| distribution volume | The volume throughout which an added tracer substance appears to have been evenly distributed, calculated by dividing the amount of tracer added by its concentration after equilibration. (05 Mar 2000) |
| t distribution | The distribution of the quotient of independent random variables, the numerator of which is a standardised normal variate and the denominator the positive square root of the quotient of a chi-square distributed variate and its number of degrees of freedom. (05 Mar 2000) |
| tissue distribution | Accumulation of a drug or chemical substance in various organs (including those not relevant to its pharmacologic or therapeutic action). This distribution depends on the blood flow or perfusion rate of the organ, the ability of the drug to penetrate organ membranes, tissue specificity, protein binding. The distribution is usually expressed as tissue to plasma ratios. (12 Dec 1998) |
| epidemiological distribution | See: histogram. (05 Mar 2000) |
| exponential distribution | The time until failure of a process at constant hazard. (05 Mar 2000) |
| f distribution | The distribution of the ratio of two independent quantities each of which is distributed like a variance in normally distributed samples. So named in honor of the English statistician and geneticist R.A. Fisher. (05 Mar 2000) |
| frequency distribution | A statistical description of raw data in terms of the number or frequency of items characterised by each of a series or range of values of a continuous variable. (05 Mar 2000) |
| lognormal distribution | If a variable y is such that x = log y, it is said to have a lognormal distribution; this is a skew distribution. (05 Mar 2000) |