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Unformatted text preview: bservations are collected serially. Robustness against departures
from independence (cont.) t-tests are not robust to departures
from independence! Example of Clustering (Grouping)
We have n subjects in ea! of "ve di#erent PE
%e response is weight loss over a set period of
We weigh ea! subject twice, but treat the data as
if ea! measurement corresponded to two persons
– NOT a good idea! Resistant Statistical Tools
A statistical procedure is “resistant” if it does not
give very di#erent results with or without a few
outliers in the data,
Example: %e median is very resistant to the presence of
outliers, but the mean may be greatly a#ected Since t-tests are based on means, the...
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- Winter '08