On Thu, 14 Mar 2013, Shane Carey wrote:
I am using the cenmle function from the NADA package and some of my data
are negative values. As a result the cenmle function will not work and
NaN's are produced. I try to change the distribution to Gaussian, but it
still will not run.
Could somebody please help me with this?
Possibly.
What do your negative values represent? If they are 'less-thans', that is,
censored as below the method detection limit or laboratory reporting limit,
then you need to transform them to absolute values and set a flag indicating
their status. For example, your data frame should have a column named 'flag'
or (the lable I use) 'ceneq1' which contains a Boolean value: zero if the
value is measured and one if it is censored.
Then write the function call similar to this:
cenmle(dataframe$value, dataframe$ceneq1, dist='lognormal')
Works as advertised.
Rich
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