Composite measure in statistics and research design refer to composite measures of
variable
Variable may refer to:
* Variable (computer science), a symbolic name associated with a value and whose associated value may be changed
* Variable (mathematics), a symbol that represents a quantity in a mathematical expression, as used in many ...
s, i.e. measurements based on multiple data items.
An example of a composite measure is an
IQ test
An intelligence quotient (IQ) is a total score derived from a set of standardized tests or subtests designed to assess human intelligence. The abbreviation "IQ" was coined by the psychologist William Stern (psychologist), William Stern for th ...
, which gives a single score based on a series of responses to various questions.
Three common composite measures include:
*
indexes
Index (or its plural form indices) may refer to:
Arts, entertainment, and media Fictional entities
* Index (''A Certain Magical Index''), a character in the light novel series ''A Certain Magical Index''
* The Index, an item on a Halo megastru ...
- measures that summarize and rank specific observations, usually on the
ordinal scale
Ordinal data is a categorical, statistical data type where the variables have natural, ordered categories and the distances between the categories are not known. These data exist on an ordinal scale, one of four levels of measurement described b ...
;
*
scales
Scale or scales may refer to:
Mathematics
* Scale (descriptive set theory), an object defined on a set of points
* Scale (ratio), the ratio of a linear dimension of a model to the corresponding dimension of the original
* Scale factor, a number w ...
- advanced indexes whose observations are further transformed (scaled) due to their logical or empirical relationships;
*
typologies - measures that classify observations in terms of their attributes on multiple variables, usually on a
nominal scale
Level of measurement or scale of measure is a classification that describes the nature of information within the values assigned to variables. Psychologist Stanley Smith Stevens developed the best-known classification with four levels, or scal ...
.
Indexes versus scales
Indexes are often referred to as scales, but in fact not all indexes are scales.
Whereas indexes are usually created by aggregating scores assigned to individual
attributes
Attribute may refer to:
* Attribute (philosophy), an extrinsic property of an object
* Attribute (research), a characteristic of an object
* Grammatical modifier, in natural languages
* Attribute (computing), a specification that defines a proper ...
of various variables, scales are more nuanced and take into account differences in intensity among the attribute of the same variable in question.
Indexes and scales should provide an
ordinal ranking of cases on a given variable, though scales are usually more efficient at this.
While indexes are based on a simple aggregation of
indicators
Indicator may refer to:
Biology
* Environmental indicator of environmental health (pressures, conditions and responses)
* Ecological indicator of ecosystem health (ecological processes)
* Health indicator, which is used to describe the health o ...
of a variable, scales are more advanced, and their calculations may be more complex, using for example scaling procedures such as
semantic differential
The semantic differential (SD) is a measurement scale designed to measure a person's subjective perception of, and affective reactions to, the properties of concepts, objects, and events by making use of a set of bipolar scales. The SD is used to a ...
.
Composite measure validation
A good composite measure will ensure that the indicators are independent of one another.
It should also successfully predict other indicators of the variable.
References
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Measurement