Global Empirical Bayes
Empirical Bayes
estimators consider the "real" rate associated with each area is not
known, and that observed
rate is available. The idea of Bayesian estimators is assumed that the actual rate is a random variable having a mean and a known variance.
The best
estimator in this rate
is a linear combination of the observed rate
(events / population) in area A
and an average value B
weighted by a factor C.
The average weight may be used in the average rate of all areas (polygons) under study, in this case, the
method is called Global Empirical Bayes.
It is
accessible through:
Plugins > Spatial Analysis >
Global
Empirical Bayes...
This
interface consists of the
following steps:
1.
Input Information:
- Layer Name: Select the
desired Layer.
2.
Operation Parameters:
- Event Attr Name:
Attribute name that identifies the desired event information.
- Population Attr Name: Attribute
name that identifies the population information.
- Rate Correction: This
is the multiplicative rate correction value.
3. Output
Information:
- Repository: Defines
where the output data will be saved.
- Layer Name: Defines the
name to create the output layer.
Click OK and then the global
bayes rate will be calculated.
Note: To calculate Bayesian Rates, the denominator (population at risk)
does not have values equal or smaller than zero.