difcurve {diffusion}

Calculates the values for various diffusion curves, given some parameters.

Description

This function calculates the values of diffusion curves that can be of "bass", "gompertz", "gsgompertz" or "weibull" type, given some parameters.

Usage

difcurve(
  n,
  w = c(0.01, 0.1, 10),
  type = c("bass", "gompertz", "gsgompertz", "weibull"),
  curve = NULL
)

Arguments

n

number of periods to calculate values for.

w

vector of curve parameters (see note). If argument curve is used, this is ignored.

type

diffusion curve to use. This can be "bass", "gompertz" and "gsgompertz". If argument curve is used, this is ignored.

curve

if provided w and type are taken from an object of class diffusion, the output of diffusion.

Value

Returns a matrix of values with each row being a period.

Note

w needs to be provided for the Bass curve in the order of ("m", "p", "q"), where "p" is the coefficient of innovation, "q" is the coefficient of imitation and "m" is the market size coefficient.

For the Gompertz curve, vector w needs to be in the form of ("m", "a", "b"). Where "a" is the x-axis displacement coefficient, "b" determines the growth rate and "m" sets, similarly to Bass model, the market potential (saturation point).

For the Shifted-Gompertz curve, vector w needs to be in the form of ("m", "a", "b", "c"). Where "a" is the x-axis displacement coefficient, "b" determines the growth rate, "c" is the shifting parameter and "m" sets, similarly to Bass model, the market potential (saturation point).

For the Weibull curve, vector w needs to be in the form of ("m", "a", "b"). Where "a" is the scale parameter, "b" determines the shape. Together, "a" and "b" determine the stepness of the curve. The "m" parameter sets the market potential (saturation point).

Author(s)

Oliver Schaer, [e-mail],

Nikolaos Kourentzes, [e-mail]

See Also

diffusion for fitting a diffusion curve.

Examples

  difcurve(w=c(0.01,0.1,10),20)