Heterogeneous is an adjective used to describe an object or system consisting of multiple items having a large number of structural variations. It is the opposite of homogeneous, which means that an object or system consists of multiple identical items. Matters of a quantum can exist in homogenous or in heterogeneous or in combined distributions. The term is often used in a scientific (such as a kind of catalyst), mathematical, sociological or statistical context.
A heterogeneous compound, mixture, reaction or other such object is one that consists of many different items, which are often not easily sorted or separated, though they are clearly distinct.
A heterogeneous mixture is a mixture of two or more compounds. In chemical kinetics, a heterogeneous reaction is one that takes place at the interface of two or more i.e. between a solid and a gas, a liquid and a gas, or a solid and a liquid. In general meaning having different states of texture such as sand and water the sand being on the bottom. Some examples: sand and iron filings a conglomerate rock water and oil, depending on who you ask, salad, trail mix, concrete (not cement).
In meta analysis the term refers to the presence of multiple non-random intercepts in a dataset. In Meta-analysis of clinical studies which involves comparing and quantifying the effects of separate studies, heterogeneity refers to the differences in study populations or in methodologies used to study them that may have the effect of reaching differing conclusions. This is a problem as it calls into question conclusions that are drawn from studies and reduces their comparability. The following concepts are important in understanding the importance of heterogeneity in meta-analytical research.
Heterogeneity resulting from differences in clinical features of a population that is being studied or treated.
Heterogeneity resulting from the differential use of study methodology. These may lead to different conclusions in different studies, despite their clinical characteristics being the same.
Heterogeneity resulting from either clinical or statistical heterogeneity, which leads to a difference in expected results, more than which can be accounted for by chance.
Distributed systems are called heterogeneous if they contain many different types of hardware and software.
In taxonomy, a heterogeneous taxon is a taxon that contains a great variety of individuals or sub-taxa; usually this implies that the taxon is an artificial grouping.
In genetics, heterogeneity refers to multiple origins causing the same disorder in different individuals.
If a number of different mutations occurring the same gene produce disorders, it is said to manifest allelic heterogeneity. This term has been used when a number of different alleles cause a similar phenotype or different phenotypes.
If mutations at a number of different loci, usually in different genes, all result in the same disorder (phenotype), such disorder is said to manifest locus heterogeneity.
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