Data Censoring and Normality Tests
I don't know much about censored data, but what you described doesn't sound like censored data, but rather truncated data. I think normality tests are over-(ab)used, and would suggest inspection of normal QQ plots instead (as you already do). For formal tests, you might be able to cook up something that test for truncated normality. Cheers, Andy
From: 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 ______________________________________________ R-help at stat.math.ethz.ch mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html