Calculating Log-likelihood for the Skew Normal Distribution in R










1














library(sn)
library(fGarch)
library(maxLik)

set.seed(12)
nl = 100
locl = 0
scalel = 1
shapel = 1

#data
y = c(rsn(n=nl, xi=locl, omega=scalel, alpha=shapel, tau=0, dp=NULL))


Assume only the shape parameter is unknown.



snormFit <- function(x, ...) 
start = c(mean = 0, sd = 1, xi = 1)

# Log-likelihood Function:
loglik = function(x, y = x)
f = -sum(log(dsnorm(y, 0, 1, x[3])))
f

# Minimization:
fit = nlminb(start = start, objective = loglik, lower = c(-Inf, 0, 0),
upper = c( Inf, Inf, Inf), y = x)

# Return Value:
fit



shape.l = snormFit(y)$par
Warning message:
In nlminb(start = start, objective = loglik, lower = c(-Inf, 0, :
NA/NaN function evaluation
> shape.l
mean sd xi
0.0000000 1.0000000 0.8216856


# Likelihood



logLik.sn = sum(log(dnorm(shape.l*y)))
Warning message:
In shape.l * y :
longer object length is not a multiple of shorter object length
logLik.sn
[1] -112.9638


IS the way I computed the log-likelihood correct? However, I am getting some warning messages. What is the reason for this? Are there any other ways to compute the log-likelihood for skew normal distribution in R?



Thank you in advance.










share|improve this question


























    1














    library(sn)
    library(fGarch)
    library(maxLik)

    set.seed(12)
    nl = 100
    locl = 0
    scalel = 1
    shapel = 1

    #data
    y = c(rsn(n=nl, xi=locl, omega=scalel, alpha=shapel, tau=0, dp=NULL))


    Assume only the shape parameter is unknown.



    snormFit <- function(x, ...) 
    start = c(mean = 0, sd = 1, xi = 1)

    # Log-likelihood Function:
    loglik = function(x, y = x)
    f = -sum(log(dsnorm(y, 0, 1, x[3])))
    f

    # Minimization:
    fit = nlminb(start = start, objective = loglik, lower = c(-Inf, 0, 0),
    upper = c( Inf, Inf, Inf), y = x)

    # Return Value:
    fit



    shape.l = snormFit(y)$par
    Warning message:
    In nlminb(start = start, objective = loglik, lower = c(-Inf, 0, :
    NA/NaN function evaluation
    > shape.l
    mean sd xi
    0.0000000 1.0000000 0.8216856


    # Likelihood



    logLik.sn = sum(log(dnorm(shape.l*y)))
    Warning message:
    In shape.l * y :
    longer object length is not a multiple of shorter object length
    logLik.sn
    [1] -112.9638


    IS the way I computed the log-likelihood correct? However, I am getting some warning messages. What is the reason for this? Are there any other ways to compute the log-likelihood for skew normal distribution in R?



    Thank you in advance.










    share|improve this question
























      1












      1








      1







      library(sn)
      library(fGarch)
      library(maxLik)

      set.seed(12)
      nl = 100
      locl = 0
      scalel = 1
      shapel = 1

      #data
      y = c(rsn(n=nl, xi=locl, omega=scalel, alpha=shapel, tau=0, dp=NULL))


      Assume only the shape parameter is unknown.



      snormFit <- function(x, ...) 
      start = c(mean = 0, sd = 1, xi = 1)

      # Log-likelihood Function:
      loglik = function(x, y = x)
      f = -sum(log(dsnorm(y, 0, 1, x[3])))
      f

      # Minimization:
      fit = nlminb(start = start, objective = loglik, lower = c(-Inf, 0, 0),
      upper = c( Inf, Inf, Inf), y = x)

      # Return Value:
      fit



      shape.l = snormFit(y)$par
      Warning message:
      In nlminb(start = start, objective = loglik, lower = c(-Inf, 0, :
      NA/NaN function evaluation
      > shape.l
      mean sd xi
      0.0000000 1.0000000 0.8216856


      # Likelihood



      logLik.sn = sum(log(dnorm(shape.l*y)))
      Warning message:
      In shape.l * y :
      longer object length is not a multiple of shorter object length
      logLik.sn
      [1] -112.9638


      IS the way I computed the log-likelihood correct? However, I am getting some warning messages. What is the reason for this? Are there any other ways to compute the log-likelihood for skew normal distribution in R?



      Thank you in advance.










      share|improve this question













      library(sn)
      library(fGarch)
      library(maxLik)

      set.seed(12)
      nl = 100
      locl = 0
      scalel = 1
      shapel = 1

      #data
      y = c(rsn(n=nl, xi=locl, omega=scalel, alpha=shapel, tau=0, dp=NULL))


      Assume only the shape parameter is unknown.



      snormFit <- function(x, ...) 
      start = c(mean = 0, sd = 1, xi = 1)

      # Log-likelihood Function:
      loglik = function(x, y = x)
      f = -sum(log(dsnorm(y, 0, 1, x[3])))
      f

      # Minimization:
      fit = nlminb(start = start, objective = loglik, lower = c(-Inf, 0, 0),
      upper = c( Inf, Inf, Inf), y = x)

      # Return Value:
      fit



      shape.l = snormFit(y)$par
      Warning message:
      In nlminb(start = start, objective = loglik, lower = c(-Inf, 0, :
      NA/NaN function evaluation
      > shape.l
      mean sd xi
      0.0000000 1.0000000 0.8216856


      # Likelihood



      logLik.sn = sum(log(dnorm(shape.l*y)))
      Warning message:
      In shape.l * y :
      longer object length is not a multiple of shorter object length
      logLik.sn
      [1] -112.9638


      IS the way I computed the log-likelihood correct? However, I am getting some warning messages. What is the reason for this? Are there any other ways to compute the log-likelihood for skew normal distribution in R?



      Thank you in advance.







      r normal-distribution skew log-likelihood






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      asked Nov 12 '18 at 19:51









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