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Inference for TwoWays Tables
 Two way categorical variables (or block design) Each intersection of
values for these two variables is called a cell. Marginal distribution is sum
of a row or column. Conditional is the sum of a row or column, keeping the
other variable constant.
The question of interest is whether there is a relation between the row
variable and the column variable. We want to know if the differences in
sample proportions are likely to have occurred just by chance, because of the
random sampling. We use the
chisquare (χ2) test
to assess the null
hypothesis of no relationship between the two categorical variables of a two
way table. These hypotheses are neither one or two tailed

H0: There is no association between the row and column
variables. H0 means that the c distributions of the row variable
are identical.

Ha: There is an association between the row and column
variables.
Ha means that the distributions are not the same
Expected counts in two way tables
We compare actual counts from the
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This note was uploaded on 02/27/2011 for the course STAT 2120 taught by Professor Jeffreyholt during the Fall '10 term at UVA.
 Fall '10
 JEFFREYHOLT
 Statistics

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