Class Exercise – Week 13
STAT 3022, section 001
12/02/2011
Analysis of
r
×
c
Table.
Consider the following 3
×
2 table of counts. Students at a public university were categorized
by how often they binge drink (never, occasionally, or frequently) and by whether they
missed a class that semester.
Missed Class
Yes
No
Binge Drink
Never
446
4617
Occasionally
915
2047
Frequently
1959
1176
(a) Calculate the marginal totals
R
1
,R
2
,R
3
,C
1
,C
2
,
and
T
.
(b) For each cell in the table, what is the
overall
proportion of students in that cell? For
example, the overall proportion of students in cell (
i,j
) is
n
ij
/T
. The distribution of
these proportions is called the
joint distribution
of the row and column variables.
(c) What is the proportion of students in our sample who missed class? What is the
proportion who didn’t miss class? This is the
marginal distribution
of Missed Class.
(d) What is the proportion of students in our sample who never binge drink? What is the
proportion who occasionally binge drink? What is the proportion who frequently binge
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 Fall '08
 Staff
 Probability theory, Chisquare distribution, binge drink

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