Sigmoid ogive

sigmoid ogive

# S4 method for FLQuant,FLPar
sigmoid(age, params, ...)

Arguments

age

FLQuant, FLPar or numeric with ages

params

FLPar with age at whick probability is 0.5 (a50) and offset to 0.95 (ato95)

...

any other arguments

Value

returns an object of same type as age e.g. FLQuant

Details

The sigmoid ogive is an S-shaped or sigmoid curve or sigmoidal functions, Verhulst hypothesizes that small populations increase geometrically, because the supply of resources exceeds demand. Then, as supply and demand balance, population growth is constant. Finally, as demand exceeds supply, population growth decreases at the same rate that it had increased. Verhulst describes this process with an equation that enables him to predict when a population will reach any given size (see Verhulst's Figure):

See also

knife, dnormal, logistic

dnormal,knife

Examples

if (FALSE) {
params=FLPar(a50=4,ato95=1)
age=FLQuant(1:10,dimnames=list(age=1:10))
sigmoid(age,params)
}