Write_jags_NEC3paramMod.R

#    Copyright 2020 Australian Institute of Marine Science
#
#    Licensed under the Apache License, Version 2.0 (the "License");
#    you may not use this file except in compliance with the License.
#    You may obtain a copy of the License at
#
#       http://www.apache.org/licenses/LICENSE-2.0
#
#    Unless required by applicable law or agreed to in writing, software
#    distributed under the License is distributed on an "AS IS" BASIS,
#    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
#    See the License for the specific language governing permissions and
#    limitations under the License.

#' write.jags.NEC3param.mod
#'
#' Writes an NEC3param model file for a three parameter model (top, beta and NEC) and generates a function for initial values to pass to jags
#'
#' @inheritParams write.jags.ECx4param.mod
#'
#' @export
#' @return an init function to pass to jags

write.jags.NEC3param.mod <- function(x = "gamma", y, mod.dat) {

  # binomial y; gamma x ----
  if (x == "gamma" & y == "binomial") {
    sink("NECmod.txt")
    cat("
        model
        {
        
        # likelihood
        for (i in 1:N)
        {
        theta[i]<-top*exp(-beta*(x[i]-NEC)*step((x[i]-NEC)))
        # response is binomial
        y[i]~dbin(theta[i],trials[i])
        }
        
        # specify model priors
        top ~  dunif(0.0001,0.999) 
        beta ~ dgamma(0.0001,0.0001)
        NEC ~ dgamma(0.0001,0.0001) #d norm(3, 0.0001) T(0,)
         
        # pearson residuals
        for (i in 1:N) {
         ExpY[i] <- theta[i]*trials[i] 
         VarY[i] <- trials[i]*theta[i] * (1 - theta[i])
         E[i] <- (y[i] - ExpY[i]) / sqrt(VarY[i])
        }
        
        # overdispersion
        for (i in 1:N) {
         ysim[i] ~  dbin(theta[i],trials[i])
         Esim[i] <- (ysim[i] - ExpY[i]) / sqrt(VarY[i])
         D[i]    <- E[i]^2     #Squared residuals for original data
         Dsim[i] <- Esim[i]^2  #Squared residuals for simulated data
        }
        SS    <- sum(D[1:N])
        SSsim <- sum(Dsim[1:N])

        }
        ", fill = TRUE)
    sink() # Make model in working directory

    init.fun <- function(mod.data = mod.data) {
      list(
        top = rbinom(1, round(mean(mod.dat$trials)), quantile(mod.dat$y / mod.dat$trials, probs = 0.75)) /
          round(mean(mod.dat$trials)),
        beta = runif(1, 0.0001, 0.999), # rlnorm(1,0,1), #
        NEC = rlnorm(1, log(mean(mod.dat$x)), 1)
      )
    } # rgamma(1,0.2,0.001))}
  }

  # binomial y; gaussian x ----
  if (x == "gaussian" & y == "binomial") {
    sink("NECmod.txt")
    cat("
        model
        {
        
        # likelihood
        for (i in 1:N)
        {
        theta[i]<-top*exp(-beta*(x[i]-NEC)*step((x[i]-NEC)))
        # response is binomial
        y[i]~dbin(theta[i],trials[i])
        }
        
        # specify model priors
        top ~  dunif(0.0001,0.999) 
        beta ~ dgamma(0.0001,0.0001)
        NEC ~ dnorm(0,0.0001) 
         
        # pearson residuals
        for (i in 1:N) {
         ExpY[i] <- theta[i]*trials[i] 
         VarY[i] <- trials[i]*theta[i] * (1 - theta[i])
         E[i] <- (y[i] - ExpY[i]) / sqrt(VarY[i])
        }
        
        # overdispersion
        for (i in 1:N) {
         ysim[i] ~  dbin(theta[i],trials[i])
         Esim[i] <- (ysim[i] - ExpY[i]) / sqrt(VarY[i])
         D[i]    <- E[i]^2     #Squared residuals for original data
         Dsim[i] <- Esim[i]^2  #Squared residuals for simulated data
        }
        SS    <- sum(D[1:N])
        SSsim <- sum(Dsim[1:N])
        
        }
        ", fill = TRUE)
    sink() # Make model in working directory

    init.fun <- function(mod.data = mod.data) {
      list(
        top = rbinom(1, round(mean(mod.dat$trials)), quantile(mod.dat$y / mod.dat$trials, probs = 0.75)) /
          round(mean(mod.dat$trials)),
        beta = runif(1, 0.0001, 0.999),
        NEC = rnorm(1, mean(mod.dat$x), 2)
      )
    }
  }

  # binomial y; beta x ----
  if (x == "beta" & y == "binomial") {
    sink("NECmod.txt")
    cat("
        model
        {
        
        # likelihood
        for (i in 1:N)
        {
        theta[i]<-top*exp(-beta*(x[i]-NEC)*step((x[i]-NEC)))
        # response is binomial
        y[i]~dbin(theta[i],trials[i])
        }
        
        # specify model priors
        top ~  dunif(0.0001,0.999) 
        beta ~ dgamma(0.0001,0.0001)
        NEC ~ dunif(0.0001,0.9999) 
         
        # pearson residuals
        for (i in 1:N) {
        ExpY[i] <- theta[i]*trials[i] 
        VarY[i] <- trials[i]*theta[i] * (1 - theta[i])
        E[i] <- (y[i] - ExpY[i]) / sqrt(VarY[i])
        }
        
        # overdispersion
        for (i in 1:N) {
        ysim[i] ~  dbin(theta[i],trials[i])
        Esim[i] <- (ysim[i] - ExpY[i]) / sqrt(VarY[i])
        D[i]    <- E[i]^2     #Squared residuals for original data
        Dsim[i] <- Esim[i]^2  #Squared residuals for simulated data
        }
        SS    <- sum(D[1:N])
        SSsim <- sum(Dsim[1:N])        
        }
        ", fill = TRUE)
    sink() # Make model in working directory

    init.fun <- function(mod.data = mod.data) {
      list(
        top = rbinom(1, round(mean(mod.dat$trials)), quantile(mod.dat$y / mod.dat$trials, probs = 0.75)) /
          round(mean(mod.dat$trials)),
        beta = runif(1, 0.0001, 0.999),
        NEC = runif(1, 0.01, 0.9)
      )
    }
  }

  # poisson y; gamma x ----
  if (x == "gamma" & y == "poisson") {
    sink("NECmod.txt")
    cat("
        model
        {
        
        # likelihood
        for (i in 1:N)
        {
        theta[i]<-top*exp(-beta*(x[i]-NEC)*step((x[i]-NEC)))
        # response is poisson
        y[i]~dpois(theta[i])
        }
        
        # specify model priors
        top ~ dgamma(1,0.001) # dnorm(0,0.001) T(0,) dnorm(100,0.0001)T(0,) #
        beta~dgamma(0.0001,0.0001)
        NEC~dgamma(0.0001,0.0001) #dnorm(3, 0.0001) T(0,) dnorm(30, 0.0001) T(0,) #
        
        # pearson residuals
        for (i in 1:N) {
         ExpY[i] <- theta[i] 
         VarY[i] <- theta[i]
         E[i]    <- (y[i] - ExpY[i]) / sqrt(VarY[i])
        }

        # overdispersion
        for (i in 1:N) {
         ysim[i] ~  dpois(theta[i])
         Esim[i] <- (ysim[i] - ExpY[i]) / sqrt(VarY[i])
         D[i]    <- E[i]^2     #Squared residuals for original data
         Dsim[i] <- Esim[i]^2  #Squared residuals for simulated data
         }
         SS    <- sum(D[1:N])
         SSsim <- sum(Dsim[1:N])

        }
        ", fill = TRUE)
    sink() # Make model in working directory

    init.fun <- function(mod.data = mod.data) {
      list(
        top = rpois(1, max(mod.dat$y)),
        beta = runif(1, 0.0001, 0.999), # rlnorm(1,0,1), #rgamma(1,0.2,0.001),
        NEC = rlnorm(1, log(mean(mod.dat$x)), 1)
      )
    } # rnorm(1,30,10))} #rgamma(1,0.2,0.001))} #
  }

  # poisson y; gaussian x----
  if (x == "gaussian" & y == "poisson") {
    sink("NECmod.txt")
    cat("
        model
        {

        # likelihood
        for (i in 1:N)
        {
        theta[i]<-top*exp(-beta*(x[i]-NEC)*step((x[i]-NEC)))
        # response is poisson
        y[i]~dpois(theta[i])
        }

        # specify model priors
        top ~  dgamma(1,0.001)
        beta~dgamma(0.0001,0.0001)
        NEC~dnorm(0, 0.0001)

        # pearson residuals
        for (i in 1:N) {
         ExpY[i] <- theta[i] 
         VarY[i] <- theta[i]
         E[i]    <- (y[i] - ExpY[i]) / sqrt(VarY[i])
        }

        # overdispersion
        for (i in 1:N) {
         ysim[i] ~  dpois(theta[i])
         Esim[i] <- (ysim[i] - ExpY[i]) / sqrt(VarY[i])
         D[i]    <- E[i]^2     #Squared residuals for original data
         Dsim[i] <- Esim[i]^2  #Squared residuals for simulated data
         }
         SS    <- sum(D[1:N])
         SSsim <- sum(Dsim[1:N])
        }
        ", fill = TRUE)
    sink() # Make model in working directory

    init.fun <- function(mod.data = mod.data) {
      list(
        top = rpois(1, max(mod.dat$y)),
        beta = rgamma(1, 0.2, 0.001),
        NEC = rnorm(1, mean(mod.dat$x), 2)
      )
    }
  }

  # poisson y; beta x----
  if (x == "beta" & y == "poisson") {
    sink("NECmod.txt")
    cat("
        model
        {
        
        # likelihood
        for (i in 1:N)
        {
        theta[i]<-top*exp(-beta*(x[i]-NEC)*step((x[i]-NEC)))
        # response is poisson
        y[i]~dpois(theta[i])
        }
        
        # specify model priors
        top ~  dgamma(1,0.001) # dnorm(0,0.001) #T(0,) #
        beta ~ dgamma(0.0001,0.0001)
        NEC ~  dunif(0.0001,0.9999) 

        # pearson residuals
        for (i in 1:N) {
         ExpY[i] <- theta[i] 
         VarY[i] <- theta[i]
         E[i]    <- (y[i] - ExpY[i]) / sqrt(VarY[i])
        }

        # overdispersion
        for (i in 1:N) {
         ysim[i] ~  dpois(theta[i])
         Esim[i] <- (ysim[i] - ExpY[i]) / sqrt(VarY[i])
         D[i]    <- E[i]^2     #Squared residuals for original data
         Dsim[i] <- Esim[i]^2  #Squared residuals for simulated data
         }
         SS    <- sum(D[1:N])
         SSsim <- sum(Dsim[1:N])
        }
        ", fill = TRUE)
    sink() # Make model in working directory

    init.fun <- function(mod.data = mod.data) {
      list(
        top = rpois(1, max(mod.dat$y)), # rnorm(1,0,1),#
        beta = rgamma(1, 0.2, 0.001),
        NEC = runif(1, 0.01, 0.9)
      )
    }
  }

  # gamma y; beta x -----
  if (x == "beta" & y == "gamma") {
    sink("NECmod.txt")
    cat("
        model
        {
        
        # likelihood
        for (i in 1:N)
        {
        theta[i]<-top*exp(-beta*((x[i])-NEC)*step(((x[i])-NEC)))
        # response is gamma
        y[i]~dgamma(shape, shape / (theta[i]))
        }
        
        # specify model priors
        top ~  dlnorm(0,0.001) #dgamma(1,0.001) # dnorm(0,0.001) #T(0,) #
        beta ~ dgamma(0.0001,0.0001)
        NEC ~  dunif(0.001,0.999) #dbeta(1,1)
        shape ~ dlnorm(0,0.001) #dunif(0,1000)

        # pearson residuals
        for (i in 1:N) {
         ExpY[i] <- theta[i] 
         VarY[i] <- shape/((shape/(shape / (theta[i])))^2)
         E[i]    <- (y[i] - ExpY[i]) / sqrt(VarY[i])
        }
        
        # overdispersion
        for (i in 1:N) {
         ysim[i] ~  dgamma(shape, shape / (theta[i]))
         Esim[i] <- (ysim[i] - ExpY[i]) / sqrt(VarY[i])
         D[i]    <- E[i]^2     #Squared residuals for original data
         Dsim[i] <- Esim[i]^2  #Squared residuals for simulated data
        }
        SS    <- sum(D[1:N])
        SSsim <- sum(Dsim[1:N])
        }
        ", fill = TRUE)
    sink() # Make model in working directory

    init.fun <- function(mod.data = mod.data) {
      list(
        top = rlnorm(1, log(quantile(mod.dat$y, probs = 0.75)), 0.1),
        beta = rgamma(1, 0.2, 0.001),
        shape = runif(1, 0, 10),
        NEC = runif(1, 0.3, 0.6)
      )
    }
  }

  # gamma y; gaussian x -----
  if (x == "gaussian" & y == "gamma") {
    sink("NECmod.txt")
    cat("
        model
        {
        
        # likelihood
        for (i in 1:N)
        {
        theta[i]<-top*exp(-beta*((x[i])-NEC)*step(((x[i])-NEC)))
        # response is gamma
        y[i]~dgamma(shape, shape / (theta[i]))
        }
        
        # specify model priors
        top ~  dlnorm(0,0.001) # dnorm(0,0.001) T(0,) #dgamma(1,0.001) #
        beta ~ dgamma(0.0001,0.0001)
        NEC ~ dnorm(0, 0.0001)
        shape ~ dlnorm(0,0.001) #dunif(0,1000)

        # pearson residuals
        for (i in 1:N) {
         ExpY[i] <- theta[i] 
         VarY[i] <- shape/((shape/(shape / (theta[i])))^2)
         E[i]    <- (y[i] - ExpY[i]) / sqrt(VarY[i])
        }
        
        # overdispersion
        for (i in 1:N) {
         ysim[i] ~  dgamma(shape, shape / (theta[i]))
         Esim[i] <- (ysim[i] - ExpY[i]) / sqrt(VarY[i])
         D[i]    <- E[i]^2     #Squared residuals for original data
         Dsim[i] <- Esim[i]^2  #Squared residuals for simulated data
        }
        SS    <- sum(D[1:N])
        SSsim <- sum(Dsim[1:N])
        }
        ", fill = TRUE)
    sink() # Make model in working directory

    init.fun <- function(mod.data = mod.data) {
      list(
        top = rlnorm(1, log(quantile(mod.dat$y, probs = 0.75)), 0.1),
        beta = rgamma(1, 0.2, 0.001),
        shape = dlnorm(1, 1 / mean(mod.dat$y), 1),
        NEC = rnorm(1, mean(mod.dat$x), 1)
      )
    }
  }

  # gamma y; gamma x -----
  if (x == "gamma" & y == "gamma") {
    sink("NECmod.txt")
    cat("
        model
        {
        
        # likelihood
        for (i in 1:N)
        {
        theta[i]<-top*exp(-beta*((x[i])-NEC)*step(((x[i])-NEC)))
        # response is gamma
        y[i]~dgamma(shape, shape / (theta[i]))
        }
        
        # specify model priors
        top ~  dlnorm(0,0.001) #dgamma(1,0.001) # dnorm(0,0.001) #T(0,) #
        beta ~ dgamma(0.0001,0.0001)
        NEC~dgamma(0.0001,0.0001) #dnorm(3, 0.0001) T(0,) dnorm(30, 0.0001) T(0,) #
        shape ~ dlnorm(0,0.001) #dunif(0,1000)

        # pearson residuals
        for (i in 1:N) {
         ExpY[i] <- theta[i] 
         VarY[i] <- shape/((shape/(shape / (theta[i])))^2)
         E[i]    <- (y[i] - ExpY[i]) / sqrt(VarY[i])
        }
        
        # overdispersion
        for (i in 1:N) {
         ysim[i] ~  dgamma(shape, shape / (theta[i]))
         Esim[i] <- (ysim[i] - ExpY[i]) / sqrt(VarY[i])
         D[i]    <- E[i]^2     #Squared residuals for original data
         Dsim[i] <- Esim[i]^2  #Squared residuals for simulated data
        }
        SS    <- sum(D[1:N])
        SSsim <- sum(Dsim[1:N])

        }
        ", fill = TRUE)
    sink() # Make model in working directory

    init.fun <- function(mod.data = mod.data) {
      list(
        top = rlnorm(1, log(quantile(mod.dat$y, probs = 0.75)), 0.1),
        beta = rgamma(1, 0.2, 0.001),
        shape = runif(1, 0, 10),
        NEC = rlnorm(1, log(mean(mod.dat$x)), 1)
      )
    } # rnorm(1,30,10))} #rgamma(1,0.2,0.001))} #
  }

  # gaussian y; gamma x ----
  if (x == "gamma" & y == "gaussian") {
    sink("NECmod.txt")
    cat("
      model
      {
      
      # likelihood
      for (i in 1:N)
      {
      theta[i]<-top*exp(-beta*(x[i]-NEC)*step((x[i]-NEC)))-alpha # extra parameter alpha is offset to y
      # response is gaussian
      
      y[i]~dnorm(theta[i],tau)
      }
      
      # specify model priors
      top ~  dnorm(0,0.1) # dnorm(0,0.001) #T(0,) 
      beta ~ dgamma(0.0001,0.0001)
      alpha ~ dnorm(0,0.1)
      NEC ~ dnorm(0, 0.0001) T(0,) #dgamma(0.0001,0.0001) Note we haven't used gamma here as the example didn't result in chain missing.
      sigma ~ dunif(0, 20)  #sigma is the SD
      tau  = 1 / (sigma * sigma)  #tau is the reciprical of the variance 

      # pearson residuals
      for (i in 1:N) {
       ExpY[i] <- theta[i] 
       VarY[i] <- tau^2
       E[i]    <- (y[i] - ExpY[i]) / sqrt(VarY[i])
      }

      # overdispersion
      for (i in 1:N) {
       ysim[i] ~  dnorm(theta[i],tau)
       Esim[i] <- (ysim[i] - ExpY[i]) / sqrt(VarY[i])
       D[i]    <- E[i]^2     #Squared residuals for original data
       Dsim[i] <- Esim[i]^2  #Squared residuals for simulated data
       }
       SS    <- sum(D[1:N])
       SSsim <- sum(Dsim[1:N])
      }
      ", fill = TRUE)
    sink() # Make model in working directory

    init.fun <- function(mod.data = mod.data) {
      list(
        top = rnorm(1, max(mod.dat$y), 1),
        beta = rgamma(1, 0.2, 0.001),
        alpha = rnorm(1, min(mod.dat$y), 1),
        NEC = rlnorm(1, log(mean(mod.dat$x)), 1), # rgamma(1,0.2,0.001),
        sigma = runif(1, 0, 5)
      )
    }
  }

  # gaussian y; beta x ----
  if (x == "beta" & y == "gaussian") {
    sink("NECmod.txt")
    cat("
        model
        {
        
        # likelihood
        for (i in 1:N)
        {
        theta[i]<-top*exp(-beta*(x[i]-NEC)*step((x[i]-NEC)))-alpha # extra parameter alpha is offset to y
        # response is gaussian
        
        y[i]~dnorm(theta[i],tau)
        }
        
        # specify model priors
        top ~  dnorm(0,0.1) # dnorm(0,0.001) #T(0,) 
        beta ~ dgamma(0.0001,0.0001)
        alpha ~ dnorm(0,0.1)
        NEC ~  dunif(0.001,0.999) #dbeta(1,1)
        sigma ~ dunif(0, 20)  #sigma is the SD
        tau  = 1 / (sigma * sigma)  #tau is the reciprical of the variance  

      # pearson residuals
        for (i in 1:N) {
        ExpY[i] <- theta[i] 
        VarY[i] <- tau^2
        E[i]    <- (y[i] - ExpY[i]) / sqrt(VarY[i])
        }
        
        # overdispersion
        for (i in 1:N) {
        ysim[i] ~  dnorm(theta[i],tau)
        Esim[i] <- (ysim[i] - ExpY[i]) / sqrt(VarY[i])
        D[i]    <- E[i]^2     #Squared residuals for original data
        Dsim[i] <- Esim[i]^2  #Squared residuals for simulated data
        }
        SS    <- sum(D[1:N])
        SSsim <- sum(Dsim[1:N])
        }
        ", fill = TRUE)
    sink() # Make model in working directory

    init.fun <- function(mod.data = mod.data) {
      list(
        top = rnorm(1, max(mod.dat$y), 1),
        beta = rgamma(1, 0.2, 0.001),
        alpha = rnorm(1, min(mod.dat$y), 1),
        NEC = runif(1, 0.3, 0.6), # rgamma(1,0.2,0.001),
        sigma = runif(1, 0, 5)
      )
    }
  }

  # gaussian y; gaussian x ----
  if (x == "gaussian" & y == "gaussian") {
    sink("NECmod.txt")
    cat("
        model
        {
        
        # likelihood
        for (i in 1:N)
        {
        theta[i]<-top*exp(-beta*(x[i]-NEC)*step((x[i]-NEC)))-alpha # extra parameter alpha is offset to y
        # response is gaussian
        
        y[i]~dnorm(theta[i],tau)
        }
        
        # specify model priors
        top ~  dnorm(0,0.1) # dnorm(0,0.001) #T(0,) 
        beta ~ dgamma(0.0001,0.0001)
        alpha ~ dnorm(0,0.1)
        NEC ~  dnorm(0,0.01)
        sigma ~ dunif(0, 20)  #sigma is the SD
        tau  = 1 / (sigma * sigma)  #tau is the reciprical of the variance 

      # pearson residuals
        for (i in 1:N) {
        ExpY[i] <- theta[i] 
        VarY[i] <- tau^2
        E[i]    <- (y[i] - ExpY[i]) / sqrt(VarY[i])
        }
        
        # overdispersion
        for (i in 1:N) {
        ysim[i] ~  dnorm(theta[i],tau)
        Esim[i] <- (ysim[i] - ExpY[i]) / sqrt(VarY[i])
        D[i]    <- E[i]^2     #Squared residuals for original data
        Dsim[i] <- Esim[i]^2  #Squared residuals for simulated data
        }
        SS    <- sum(D[1:N])
        SSsim <- sum(Dsim[1:N])
        }
        ", fill = TRUE)
    sink() # Make model in working directory

    init.fun <- function(mod.data = mod.data) {
      list(
        top = rnorm(1, max(mod.dat$y), 1),
        beta = rgamma(1, 0.2, 0.001),
        alpha = rnorm(1, min(mod.dat$y), 1),
        NEC = rnorm(1, mean(mod.dat$x), 1),
        sigma = runif(1, 0, 5)
      )
    }
  }

  # beta y; beta x ----
  if (x == "beta" & y == "beta") {
    sink("NECmod.txt")
    cat("
        model
        {
        
        # likelihood
        for (i in 1:N)
        {

        # response is beta
        y[i]~dbeta(shape1[i], shape2[i])
        shape1[i] <- theta[i] * phi
        shape2[i]  <- (1-theta[i]) * phi
        theta[i]<-top*exp(-beta*((x[i])-NEC)*step(((x[i])-NEC)))
        }
        
        # specify model priors
        top ~  dunif(0.001,0.999)
        beta ~ dgamma(0.0001,0.0001)
        NEC ~  dunif(0.001,0.999) #dbeta(1,1)
        t0 ~ dnorm(0, 0.010)
        phi <- exp(t0)

        # pearson residuals
        for (i in 1:N) {
         ExpY[i] <- theta[i] 
         VarY[i] <- (shape1[i]*shape2[i])/((shape1[i]+shape2[i])^2*(shape1[i]+shape2[i]+1))
         E[i] <- (y[i] - ExpY[i]) / sqrt(VarY[i])
        }
        
        # overdispersion
        for (i in 1:N) {
         ysim[i] ~ dbeta(shape1[i], shape2[i])
         Esim[i] <- (ysim[i] - ExpY[i]) / sqrt(VarY[i])
         D[i]    <- E[i]^2     #Squared residuals for original data
         Dsim[i] <- Esim[i]^2  #Squared residuals for simulated data
        }
        SS    <- sum(D[1:N])
        SSsim <- sum(Dsim[1:N])
        }
        ", fill = TRUE)
    sink() # Make model in working directory

    init.fun <- function(mod.data = mod.data) {
      list(
        top = rlnorm(1, log(quantile(mod.dat$y, probs = 0.75)), 0.1),
        beta = rgamma(1, 0.2, 0.001),
        t0 = rnorm(0, 100),
        NEC = runif(1, 0.3, 0.6)
      )
    }
  }

  # beta y; gamma x ----
  if (x == "gamma" & y == "beta") {
    sink("NECmod.txt")
    cat("
        model
        {
        
        # likelihood
        for (i in 1:N)
        {
        
        # response is beta
        y[i] ~ dbeta(shape1[i], shape2[i])
        shape1[i] <- theta[i] * phi
        shape2[i]  <- (1-theta[i]) * phi
        theta[i]<-top*exp(-beta*((x[i])-NEC)*step(((x[i])-NEC)))
        }
        
        # specify model priors
        top ~  dunif(0.001,0.999)
        beta ~ dgamma(0.0001,0.0001)
        NEC ~ dgamma(0.0001,0.0001) 
        t0 ~ dnorm(0, 0.010)
        phi <- exp(t0)

        # pearson residuals
        for (i in 1:N) {
         ExpY[i] <- theta[i] 
         VarY[i] <- (shape1[i]*shape2[i])/((shape1[i]+shape2[i])^2*(shape1[i]+shape2[i]+1))
         E[i] <- (y[i] - ExpY[i]) / sqrt(VarY[i])
        }
        
        # overdispersion
        for (i in 1:N) {
         ysim[i] ~ dbeta(shape1[i], shape2[i])
         Esim[i] <- (ysim[i] - ExpY[i]) / sqrt(VarY[i])
         D[i]    <- E[i]^2     #Squared residuals for original data
         Dsim[i] <- Esim[i]^2  #Squared residuals for simulated data
        }
        SS    <- sum(D[1:N])
        SSsim <- sum(Dsim[1:N])
        }
        ", fill = TRUE)
    sink() # Make model in working directory

    init.fun <- function(mod.data = mod.data) {
      list(
        top = dunif(0.001, 0.999),
        beta = rgamma(1, 0.2, 0.001),
        t0 = rnorm(0, 100),
        NEC = rlnorm(1, log(mean(mod.dat$x)), 1)
      )
    }
  }

  # beta y; gaussian x ----
  if (x == "gaussian" & y == "beta") {
    sink("NECmod.txt")
    cat("
        model
        {
        
        # likelihood
        for (i in 1:N)
        {
        
        # response is beta
        y[i]~dbeta(shape1[i], shape2[i])
        shape1[i] <- theta[i] * phi
        shape2[i]  <- (1-theta[i]) * phi
        theta[i]<-top*exp(-beta*((x[i])-NEC)*step(((x[i])-NEC)))
        }
        
        # specify model priors
        top ~  dunif(0.001,0.999)
        beta ~ dgamma(0.0001,0.0001)
        NEC ~ dnorm(0, 0.0001)
        t0 ~ dnorm(0, 0.010)
        phi <- exp(t0)

        # pearson residuals
        for (i in 1:N) {
        ExpY[i] <- theta[i] 
        VarY[i] <- (shape1[i]*shape2[i])/((shape1[i]+shape2[i])^2*(shape1[i]+shape2[i]+1))
        E[i] <- (y[i] - ExpY[i]) / sqrt(VarY[i])
  }
        
        # overdispersion
        for (i in 1:N) {
        ysim[i] ~ dbeta(shape1[i], shape2[i])
        Esim[i] <- (ysim[i] - ExpY[i]) / sqrt(VarY[i])
        D[i]    <- E[i]^2     #Squared residuals for original data
        Dsim[i] <- Esim[i]^2  #Squared residuals for simulated data
        }
        SS    <- sum(D[1:N])
        SSsim <- sum(Dsim[1:N])
        }
        ", fill = TRUE)
    sink() # Make model in working directory

    init.fun <- function(mod.data = mod.data) {
      list(
        top = dunif(0.001, 0.999),
        beta = rgamma(1, 0.2, 0.001),
        t0 = rnorm(0, 100),
        NEC = rnorm(1, 0, 2)
      )
    }
  }

  # negbin y; gaussian x ----
  if (x == "gaussian" & y == "negbin") {
    sink("NECmod.txt")
    cat("
        model
        {
        
        # likelihood
        for (i in 1:N)
        {
        theta[i]<-size/(size+top*exp(-beta*(x[i]-NEC)*step((x[i]-NEC))))
        # response is begative binomial
        y[i]~dnegbin(theta[i], size)
        }
        
        # specify model priors
        top ~ dgamma(1,0.001) # dnorm(0,0.001) T(0,) dnorm(100,0.0001)T(0,) #
        beta ~ dgamma(0.0001,0.0001)
        NEC ~ dnorm(0.0001,0.0001) #dnorm(3, 0.0001) T(0,) dnorm(30, 0.0001) T(0,) #
        size ~ dunif(0,50)
        
        # pearson residuals
        for (i in 1:N) {
        ExpY[i] <- theta[i] 
        VarY[i] <- theta[i] + theta[i] * theta[i] / size
        E[i]    <- (y[i] - ExpY[i]) / sqrt(VarY[i])
        }
        
        # overdispersion
        for (i in 1:N) {
        ysim[i] ~  dnegbin(theta[i], size)
        Esim[i] <- (ysim[i] - ExpY[i]) / sqrt(VarY[i])
        D[i]    <- E[i]^2     #Squared residuals for original data
        Dsim[i] <- Esim[i]^2  #Squared residuals for simulated data
        }
        SS    <- sum(D[1:N])
        SSsim <- sum(Dsim[1:N])
        
        }
        ", fill = TRUE)
    sink() # Make model in working directory

    init.fun <- function(mod.data = mod.data) {
      list(
        top = rpois(1, max(mod.dat$y)),
        beta = runif(1, 0.0001, 0.999), # rlnorm(1,0,1), #rgamma(1,0.2,0.001),
        NEC = rnorm(1, mean(mod.dat$x), 1), # rnorm(1,30,10))} #rgamma(1,0.2,0.001)),
        size = runif(1, 0.1, 40)
      )
    } #
  }

  # negbin y; gamma x ----
  if (x == "gamma" & y == "negbin") {
    sink("NECmod.txt")
    cat("
        model
        {
        
        # likelihood
        for (i in 1:N)
        {
        theta[i]<-size/(size+top*exp(-beta*(x[i]-NEC)*step((x[i]-NEC))))
        # response is begative binomial
        y[i]~dnegbin(theta[i], size)
        }
        
        # specify model priors
        top ~ dgamma(1,0.001) # dnorm(0,0.001) T(0,) dnorm(100,0.0001)T(0,) #
        beta ~ dgamma(0.0001,0.0001)
        NEC~dgamma(0.0001,0.0001) #dnorm(3, 0.0001) T(0,) dnorm(30, 0.0001) T(0,) #
        size ~ dunif(0,50)
        
        # pearson residuals
        for (i in 1:N) {
        ExpY[i] <- theta[i] 
        VarY[i] <- theta[i] + theta[i] * theta[i] / size
        E[i]    <- (y[i] - ExpY[i]) / sqrt(VarY[i])
        }
        
        # overdispersion
        for (i in 1:N) {
        ysim[i] ~  dnegbin(theta[i], size)
        Esim[i] <- (ysim[i] - ExpY[i]) / sqrt(VarY[i])
        D[i]    <- E[i]^2     #Squared residuals for original data
        Dsim[i] <- Esim[i]^2  #Squared residuals for simulated data
        }
        SS    <- sum(D[1:N])
        SSsim <- sum(Dsim[1:N])
        
        }
        ", fill = TRUE)
    sink() # Make model in working directory

    init.fun <- function(mod.data = mod.data) {
      list(
        top = rpois(1, max(mod.dat$y)),
        beta = runif(1, 0.0001, 0.999), # rlnorm(1,0,1), #rgamma(1,0.2,0.001),
        NEC = rlnorm(1, log(mean(mod.dat$x)), 1), # rnorm(1,30,10))} #rgamma(1,0.2,0.001)),
        size = runif(1, 0.1, 40)
      )
    } #
  }

  # negbin y; beta x ----
  if (x == "beta" & y == "negbin") {
    sink("NECmod.txt")
    cat("
        model
        {
        
        # likelihood
        for (i in 1:N)
        {
        theta[i]<-size/(size+top*exp(-beta*(x[i]-NEC)*step((x[i]-NEC))))
        # response is begative binomial
        y[i]~dnegbin(theta[i], size)
        }
        
        # specify model priors
        top ~ dgamma(1,0.001) # dnorm(0,0.001) T(0,) dnorm(100,0.0001)T(0,) #
        beta ~ dgamma(0.0001,0.0001)
        NEC ~  dunif(0.001,0.999) #dbeta(1,1)
        size ~ dunif(0,50)
        
        # pearson residuals
        for (i in 1:N) {
        ExpY[i] <- theta[i] 
        VarY[i] <- theta[i] + theta[i] * theta[i] / size
        E[i]    <- (y[i] - ExpY[i]) / sqrt(VarY[i])
        }
        
        # overdispersion
        for (i in 1:N) {
        ysim[i] ~  dnegbin(theta[i], size)
        Esim[i] <- (ysim[i] - ExpY[i]) / sqrt(VarY[i])
        D[i]    <- E[i]^2     #Squared residuals for original data
        Dsim[i] <- Esim[i]^2  #Squared residuals for simulated data
        }
        SS    <- sum(D[1:N])
        SSsim <- sum(Dsim[1:N])
        
        }
        ", fill = TRUE)
    sink() # Make model in working directory

    init.fun <- function(mod.data = mod.data) {
      list(
        top = rpois(1, max(mod.dat$y)),
        beta = runif(1, 0.0001, 0.999),
        NEC = runif(1, 0.3, 0.6),
        size = runif(1, 0.1, 40)
      )
    }
  }

  # return the initial function
  if (exists("init.fun")) {
    return(init.fun)
  }
  else {
    stop(paste("jagsNEC does not currently support ", x, " distributed concentration data with ", y,
      " distributed response data. Please check this is the correct distribution to use, and if so
          feel free to contact the developers to request to add this distribution",
      sep = ""
    ))
  }
}