Ecological correlation
Encyclopedia
In statistics
, an ecological correlation is a correlation
between two variables that are group mean
s, in contrast to a correlation between two variables that describe individuals. For example, one might study the correlation between physical activity and weight among sixth-grade children. A study at the individual level might make use of 100 children, then measure both physical activity and weight; the correlation between the two variables would be at the individual level. By contrast, another study might make use of 100 classes of sixth-grade students, then measure the mean physical activity and the mean weight of each of the 100 classes. A correlation between these group means would be an example of an ecological correlation. Because most natural phenomena are spatially autocorrelated groupings are often spatial, sometimes they are categorical instead.
Assuming that what holds true for the group also holds true for the individual is often called the ecological fallacy
. When the fallacy can be avoided, some researchers suggest that the ecological correlation gives a better picture of the outcome of public policy actions, thus they recommend the ecological correlation over the individual level correlation for this purpose (Lubinski & Humphreys, 1996).
Specific applications
Statistics
Statistics is the study of the collection, organization, analysis, and interpretation of data. It deals with all aspects of this, including the planning of data collection in terms of the design of surveys and experiments....
, an ecological correlation is a correlation
Correlation
In statistics, dependence refers to any statistical relationship between two random variables or two sets of data. Correlation refers to any of a broad class of statistical relationships involving dependence....
between two variables that are group mean
Mean
In statistics, mean has two related meanings:* the arithmetic mean .* the expected value of a random variable, which is also called the population mean....
s, in contrast to a correlation between two variables that describe individuals. For example, one might study the correlation between physical activity and weight among sixth-grade children. A study at the individual level might make use of 100 children, then measure both physical activity and weight; the correlation between the two variables would be at the individual level. By contrast, another study might make use of 100 classes of sixth-grade students, then measure the mean physical activity and the mean weight of each of the 100 classes. A correlation between these group means would be an example of an ecological correlation. Because most natural phenomena are spatially autocorrelated groupings are often spatial, sometimes they are categorical instead.
Assuming that what holds true for the group also holds true for the individual is often called the ecological fallacy
Ecological fallacy
An ecological fallacy is a logical fallacy in the interpretation of statistical data in an ecological study, whereby inferences about the nature of specific individuals are based solely upon aggregate statistics collected for the group to which those individuals belong...
. When the fallacy can be avoided, some researchers suggest that the ecological correlation gives a better picture of the outcome of public policy actions, thus they recommend the ecological correlation over the individual level correlation for this purpose (Lubinski & Humphreys, 1996).
See also
General topics- Geographic information scienceGeographic Information ScienceGeographic information science is the academic theory behind the development, use, and application of geographic information systems...
- Spatial autocorrelation
- Complete spatial randomnessComplete spatial randomnessComplete spatial randomness describes a point process whereby point events occur within a given study area in a completely random fashion. Such a process is often modeled using only one parameter, i.e. the density of points, \rho within the defined area...
- Modifiable Areal Unit ProblemModifiable Areal Unit ProblemThe modifiable areal unit problem is a source of statistical bias that can radically affect the results of statistical hypothesis tests. It affects results when point-based measures of spatial phenomena are aggregated into districts. The resulting summary values are influenced by the choice of...
Specific applications
- Spatial epidemiologySpatial epidemiologySpatial epidemiology is a subfield of health geography focused on the study of the spatial distribution of disease.-See also:General topics* Cluster * Complete spatial randomness* Geographic information system* Geographic information science...
- Spatial econometricsSpatial econometricsSpatial Econometrics is the field where spatial analysis and econometrics intersect. In general, econometrics differs from other branches of statistics in focusing on theoretical models, whose parameters are estimated using regression analysis...