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When Not to Use the Mean
Statistical
criteria
•In the presence of
heavy tails (outliers)
–the mean is not
estimated with high precision
–asymptotic
distributional theory may not yet hold
•When adjusting for
covariates, it may be unreasonable to expect the mean to show
constant differences across subgroups
–Especially invoked
with binary data
•(we most often use the
odds instead)