Heterogeneous

Heterogeneous (, also (American English)) means that something (an object or system) consists of a diverse range of different items. It is the antonym of homogeneous, which means that an object or system consists of many identical items. The term is often used in a scientific (such as a kind of catalyst), mathematical, sociological or statistical context.

Statistics
In meta analysis the term refers to the presence of multiple 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 use 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.

Clinical Heterogeneity:

Heterogeneity resulting from differences in clinical features of a population that is being studied or treated.

Methodological Heterogeneity:

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.

Statistical Heterogeneity:

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.

Systems
In the world of enterprise computing, heterogeneous data is a mix of data from two or more sources, often of two or more formats, e.g., SQL and XML.

Distributed systems are called heterogeneous if they contain many different types of hardware and software.

Social and human science
Homogeneity and heterogeneity are terms used to describe various aspects of human groups, communities and populations, including cultural, demographic, ethnic and socio-political. In Economics and Social Sciences, a set of agents with different properties.

General
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.

Genetics
In genetics heterogeneity refers to multiple origins of a disorder.

Allelic heterogeneity

If a number of different mutations at the same locus (same gene) produce same disorder such disorder is said to manifest allelic heterogeneity

Example Disease:

Beta-Thalessemia can be caused by a number of different mutations in beta-globin gene.

Locus Heterogeneity

If mutations at a number of different loci result in a disorder such disorder is said to manifest locus heterogeneity.

Example Disease

Retinitis Pigmentosa has autosomal dominant, autosomal recessive, and x-linked origins.