Statistics for Censored Environmental Data
NADA Course Outline
Day 1
Types of Reporting Limits
detection
and quantitation limits
implications
for data analysisStoring Nondetects in a Database
three
standard formatsPlotting Data with Nondetects
censored
boxplots
censored
probability plots
scatterplots
with nondetects
survival
curvesOverview: The Three Approaches
ROS
(probability plotting)
maximum
likelihood
nonparametric
methods
why
not to substitute (fabricate) dataEstimating Descriptive Statistics
what's
the mean of <1, 5 <10 and 17?
parametric
methods
Kaplan-Meier
and other nonparametric methods
why
Cohen and Delta-lognormal are “old
technology”Computing Interval Estimates
how
to compute confidence intervals with
nondetects
UCLs
for censored data
bootstrappingTests for paired data
paired
Prentice-Wilcoxon test
paired
“t-test” for censored dataDay 2
Comparing Two Groups
Generalized
Wilcoxon (nonparametric) test
MLE
“t-test”
what
to do with multiple reporting limitsComparing Three or More Groups
Generalized
Wilcoxon (nonparametric) test
MLE
version of ANOVA
familiar
tests for one reporting limitCorrelation Methods
censored
correlation coefficients
what
to do when one or both have multiple detection limits?
Kendall’s
tau
likelihood
correlation coefficientRegression and Trends
how
to compute a line with nondetects?
what
to do with multiple reporting limits?
Akritas-Sen-Theil
line
MLE
for regression
logistic
regression