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CHURCH ATTENDANCE CAUSES DRINKING
In cross-sectional analysis, one would select a number of cities
and for each city record the number of churches and the
number of bars noting that the more churches that were in a city
the more the number of bars. Curious, but true.
# of # of
city # churches bars
1 10 14
2 15 20
.... .... .....
n 23 36
In time series analysis, one would select one city and
research the historical archives and determine what the
number of churches and the number of bars were at different
points in time.
# of # of
Year churches bars
1 20 29
2 29 41
.... .... .....
n 45 71
Perhaps a concomitant variable lurking in the back ground ? The
concommitant variable could be population or even the ethnicity
of the city. Perhaps the number of people of a certain type build
more churches and bars ? If the true cause variable is brought into
the model the apparaent association disappears.
IS VOCABULARY RELATED TO FOOT SIZE ?
Another example... the relationship between
length of foot and number of words in vocabulary in the
school-age (K-12) population. If you control for age, the
correlation disappears...
WHY IS IT THAT STUDENTS WHO USE TUTORS HAVE LOWER
TEST SCORES THAN STUDENTS WHO DON'T ?
The answer is simply students with good test scores simply
don't use tutors.
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