[R] Data Censoring and Normality Tests

[Kenneth Frost]

Hello,

I would like to know if there is a function in R that will test for 
normality and handle censored data sets.  Currently, I evaluate each 
censored data set by the extent to which a normal scores plot 
approximate a straight line.  For complete data sets I use 
shapiro.test().

Below is an example of a censored data set.

data1<-c(0.00, 0.00, 0.00, 5.86, 5.17,  8.17,  5.12, 4.92, 7.08, 5.73, 
5.44, 6.61, 6.34, 6.23, 5.97, 5.86, 5.15, 7.98, 6.72, 5.15, 3.58, 6.86, 
6.12, 4.58, 6.07, 5.38, 5.21, 3.78)

The zero values occur because I cannot detect a pathogen with a value 
below 2.4.  Using shapiro.test(), it seems that the data are different 
from a normal distribution.  However, the normal scores plot suggest 
otherwise.

Using R version 1.9.1

Thanks in advance.

Ken
________________________________________________________
Kenneth E. Frost
Research Assistant
University of Wisconsin - Madison
Dept. of Plant Pathology
1630 Linden Dr.
Madison, WI 53706
kef at plantpath.wisc.edu