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Allergies by U. S. Region: Determining Degrees of Freedom

APSTAT-UEHDKG

As part of the 2012 National Health Interview Survey, the U. S. Census Bureau collected data from about $73,661$ children under the age of 18 years. The report provided frequencies of different types of allergies for these children and frequencies were broken down by U. S. region.

Data is shown in the table below:

No Allergies Hay Fever Respiratory Allergies Food Allergies Skin Allergies
Northeast 7,776 1,074 1,108 698 1,321
Midwest 10,966 1,310 1,684 937 1,900
South 16,132 2,621 3,452 1,554 3,476
West 11,413 1,636 1,581 910 2,112



How many degrees of freedom would be used when conducting a ${ \chi }^{ 2 }$ test to see if there is evidence of an association between U. S. region and types of allergies in children under the age of 18?

A

$4$

B

$5$

C

$12$

D

$20$

E

$73,660$