BA 253: Business Statistics 11/14/08
Today Next Week
More χ2 Tests Linear Regession
ICE 10
χ 2
Tests.
Compare two or more proportions.
Only tests same or different.
Rule: If χ2 test statistic is small, then expected ≈ observed, accept H0, props are same.
If χ2 test statistic is big, then expected ≠ observed, reject H0, props are different.
Ex C: Assume you won a contest and could choose one of three prizes. Then survey 50
responses from Durango, Denver, and Aspen.
A: New Volvo
B: New Subaru + $15,000
C: Beat up Pickup + $30,000
H0: same proportions H0: independent variables
Ha: different proportions Ha: dependent variables
H0: no relationship among variables
Ha: a relationship exists
H0: Residents of each town would choose prizes with same proportions
Ha: Residents would choose different proportions
H0: Prize choice is independent of where you live
Ha: Prize choice depends on where you live
H0: Town and prize choice are not related
Ha: A relationship exists between prize choice and where you’re from
Ex D): Do skiers, snowboarders, and telemark skiers prefer different ski areas? Assume
that 100 riders from each group were surveyed and asked whether they prefer Purgatory,
Telluride, Wolf Creek Pass, or the Silverton. The data is below. At = 5%, do different
types of snow enthusiasts prefer skiing in different areas?
Wolf Creek Telluride DMR Silverton
Snowboarders 25 30 10 35
Skiers 20 25 35 20
Telemarkers 20 25 5 50
D-go Denver Aspen
Volvo
Sub+$15k
Truck+$30k
