Parameter estimates from a nonlinear lest squares (NLS) fit.

This function converts the estimated parameters from the non-linear least squares (NLS) model fit to the appropriate parameter space corresponding to the cosine model proposed by Balasse et al (2012).

Usage

convertParameters(curve)

Arguments

curve: A fitted model object from nls function. The fitted model should have the following parameter estimates - amplitude, intercept, frequency, phase.

Value

A list containing the following components:

amplitude: estimated amplitude
intercept: estimated intercept
x0: delay of the data
X: period of the data
birth: birth seasonality estimate

Examples

armenia_split = split(armenia,f = armenia$ID)
curve = sineFit(armenia_split[[1]],method = "OLS")
convertParameters(curve)
#> $amplitude
#> amplitude 
#>    5.2653 
#> 
#> $intercept
#> intercept 
#> -4.248525 
#> 
#> $x0
#>    phase 
#> 33.27088 
#> 
#> $X
#> frequency 
#>  37.91834 
#> 
#> $birth
#>     phase 
#> 0.8774349 
#>