| discrete time model | <epidemiology> A model in which the system jumps from one state to the next at fixed intervals or timesteps. These difference models are simple to understand but often difficult to analyse; Contrast continuous time models. The parameters in such a model refer to the amount of change over the finite timestep; they are sometimes referred to as finite rates. In a (rather precise) sense, a differential equation is what you eventually get from a difference equation when you let the timestep get smaller and smaller and smaller. (05 Dec 1998) |
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| continuous time model | <epidemiology> A model in which the system changes continuously over time. Derivatives (e.g. DY/dt ) are the mathematical formalism for describing such continuous change. The differential equation which embodies a model provides the values of these derivatives at any particular time point; calculus or a computer can then be used to move the state of the model forwards in time. Continuous models have the advantage over discrete time models in that they are more amenable to algebraic manipulation, although they are slightly harder to implement on a computer. The same as a differential equation model. (05 Dec 1998) |
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| mixed discrete-continuous random variable | <statistics> A random variable that may assume some values with probabilities and others with probability densities. For example, in a 35-year-old man with familial polyposis of the colon, the distribution of time until malignant disease occurs consists of a probability that he already has cancer (which would be assigned the waiting time 0), a probability density of developing it in the future and a probability that he will die of some other cause before he develops cancer. (05 Mar 2000) |
| discrete | 1. Separate; distinct; disjunct. 2. Disjunctive; containing a disjunctive or discretive clause; as, "I resign my life, but not my honor," is a discrete proposition. 3. <botany> Separate; not coalescent; said of things usually coalescent. Discrete movement. See Concrete movement of the voice, under Concrete, Discrete proportion, proportion where the ratio of the means is different from that of either couplet; as, 3:6::8:16, 3 bearing the same proportion to 6 as 8 does to 16. But 3 is not to 6 as 6 to 8. It is thus opposed to continued or continual proportion; as, 3:6::12:24. Discrete quantity, that which must be divided into units, as number, and is opposed to continued quantity, as duration, or extension. Origin: L. Discretus, p. P. Of discernere. See Discreet. Source: Websters Dictionary (01 Mar 1998) |
| discrete character | Classifiable character that is also countable (e.g., number of progeny, number of teeth). Synonym: discrete character. (05 Mar 2000) |
| discrete random variable | A random variable that may assume a countable number of values, each with a probability strictly greater than zero. (05 Mar 2000) |
| discrete smallpox | The usual form in which the lesions are separate and distinct from each other. (05 Mar 2000) |
| discrete variable | A variable that may assume only a countable (usually finite) number of values. (05 Mar 2000) |
| Adair-Koshland-Nemethy-Filmer model | <biochemistry, chemistry> A model to explain the allosteric form of cooperativity; in this model, in the absence of ligands, the protein exists in only one conformation; upon binding, the ligand induces a conformational change that may be transmitted to other subunits. Synonym: Adair-Koshland-Nemethy-Filmer model, induced fit model. (05 Mar 2000) |
| additive model | A model in which the combined effect of several factors is the sum of the effects that would be produced by each of the factors in the absence of the others. (05 Mar 2000) |
| age-structured model | <epidemiology> A mathematical model which take into consideration the division of the host population into different age classes. Such models can used to consider the consequences of such factors as age-dependent infection, morbidity or mortality rates or of age-specific vaccination schedules. (05 Dec 1998) |
| animal model | Study in a population of laboratory animals that uses conditions of animals analogous to conditions of humans to simulate processes comparable to those that occur in human populations. (05 Mar 2000) |
| Bingham model | A model representing the flow behaviour of a Bingham plastic, in the idealised case. (05 Mar 2000) |
| biomedical model | A conceptual model of illness that excludes psychological and social factors and includes only biological factors in an attempt to understand a person's medical illness or disorder. (05 Mar 2000) |
| biopsychosocial model | A conceptual model that assumes that psychological and social factors must also be included along with the biological in understanding a person's medical illness or disorder. (05 Mar 2000) |
| genetic model | A formalised conjecture about the behaviour of a heritable structure in which the component terms are intended to have literal interpretation as standard structures of empirical genetics. (05 Mar 2000) |