evidence {qpcR} | R Documentation |
The evidence ratio
frac{1}{exp(-0.5 * (AIC2 - AIC1))}
is calculated for fitted models either from two 'drc' objects or two numerical values. Models can be compared that are not nested and where the f-test on residual-sum-of-squares is not applicable.
evidence(x, y, type = c("AICc", "AIC"))
x |
a 'drc' object or numerical value. |
y |
a 'drc' object or numerical value. |
type |
Bias-corrected (AICc , default) or original (AIC ) versions of the Akaike Information Criterion. |
Small differences in AIC values can mean substantial more 'likelihood' of one model over the other. For example, a model with AIC = -130 is nearly 150 times more likely than a model with AIC = -120. Unfortunately, not yet a generic function, so works only with 'drc' objects.
A value of the first model x
being more likely than the second model y
.
If large, first model is better. If small, second model is better.
Andrej-Nikolai Spiess
### compare two models, four-parameter and five-parameter m1 <- pcrfit(reps, 1, 2, l4()) m2 <- pcrfit(reps, 1, 2, l5()) evidence(m2, m1) ### ratio of two AIC's evidence(-120, -123)