title: Error in subset.default(data, Parameter == parm) : object 'Parameter' not found while running example in cenGAM package
body: <p>I am running the example of <code>Tobit I</code> regression using <code>GAM</code> model with the <code>cenGAM</code> package.
  However, running the example provided in the manual of the package gave me the following error:</p>
  
  <blockquote>
    <p>Error in subset.default(data, Parameter == parm) : 
      object 'Parameter' not found</p>
  </blockquote>
  
  <p>Here is the code I ran:`</p>
  
  <pre><code>library(cenGAM)
  
  # Generate random data
  set.seed(1)
  x &lt;- matrix(2*rnorm(300), 100)
  yn &lt;- 2*x[,3] + 4*cos(x[,1]*2)
  y &lt;- yn + rnorm(100)
  ycensored &lt;- pmax(y, 0) # data left-censored at 0
  ycensored &lt;- pmin(ycensored, 4) # data right-censored at 4
  par(mfrow = c(3,3))
  # True model
  plot(gam(y ~ s(x[,1]) + s(x[,2]) + s(x[, 3])), ylim=c(-5, 5), main = "True")
  # Naive estimation
  plot(gam(ycensored ~ s(x[,1]) + s(x[,2]) + s(x[, 3])), ylim=c(-5, 5), main = "Naive")
  # Tobit I estimation
  m &lt;- gam(ycensored ~ s(x[,1]) + s(x[,2]) + s(x[, 3]), family = tobit1(left.threshold=0))
  </code></pre>
  
  <p>Everything worked fine until I ran the last line of the code to fit the <code>Tobit 1</code> GAM model.
  Could any one know how to fix it?</p>
  
  <p>I am using <code>R 3.4.1</code></p>