add1_AIC: Add one possible covariate on GEV parameter based on AIC
In pengyuwei94/evreg: Extreme value regression modelling

Description Usage Arguments Value Examples

Add a single term to either mu, sigma, and xi based on AIC.

1	add1_AIC_mu(fit)

fit

An object of class c("gev", "evreg") returned from gevreg summarising the current model fit.

An object (a list) of class c("gev", "evreg") summarising the new model fit (which may be the same as fit) and containing the following additional components

`Input_fit`	The input object of the class `c("gev", "evreg")`.
`Note`	A message that tells if a covariate has been added or not.
`Output_fit`	A list that contains formulae for the parameter, and the output object of the class `c("gev", "evreg")` if the output fit is different from the input fit.
`added_covariate`	A character vector shows added covariate
`AIC`	AIC values for both input model and output model if two models are different.

### Fremantle sea levels
# Parameter mu
f0 <- gevreg(SeaLevel, data = evreg::fremantle[,-1])
add1_AIC_mu(f0)

# Parameter sigma
f3 <- gevreg(y = SeaLevel, data = evreg::fremantle[,-1], mu = ~Year01 + SOI)
add1_AIC_sigma(f3)

# Parameter xi
f4 <- gevreg(y = SeaLevel, data = evreg::fremantle[,-1], mu = ~Year01 + SOI, sigma = ~SOI)
add1_AIC_xi(f4)


### Annual Maximum and Minimum Temperature

P0 <- gevreg(y = TMX1, data = PORTw[, -1])
add1_AIC_mu(P0)
add1_AIC_sigma(P0)
add1_AIC_xi(P0)