In: Statistics and Probability
60. A recent debate about where in the United States skiers believe the skiing is best prompted the following survey. Test to see if the best ski area is independent of the level of the skier. U.S. Ski Area Beginner Intermediate Advanced Tahoe 20 30 40 Utah 10 30 60 Colorado 10 40 50 .
Ho: Best ski area is independent of the level of the skier
Ha: Best ski area is dependent on the level of the skier
Chi-Square Test of independence | |||||||
Observed Frequencies | |||||||
0 | |||||||
U.S Ski Area | Beginner | Intermediate | Advanced | Total | |||
Tahoe | 20 | 30 | 40 | 90 | |||
Utah | 10 | 30 | 60 | 100 | |||
Colorado | 10 | 40 | 50 | 100 | |||
Total | 40 | 100 | 150 | 290 | |||
Expected frequency of a cell = sum of row*sum of column / total sum | |||||||
Expected Frequencies | |||||||
Beginner | Intermediate | Advanced | Total | ||||
Tahoe | 40*90/290=12.414 | 100*90/290=31.034 | 150*90/290=46.552 | 90 | |||
Utah | 40*100/290=13.793 | 100*100/290=34.483 | 150*100/290=51.724 | 100 | |||
Colorado | 40*100/290=13.793 | 100*100/290=34.483 | 150*100/290=51.724 | 100 | |||
Total | 40 | 100 | 150 | 290 | |||
(fo-fe)^2/fe | |||||||
Tahoe | 4.6360 | 0.0345 | 0.922 | ||||
Utah | 1.0431 | 0.5828 | 1.324 | ||||
Colorado | 1.0431 | 0.8828 | 0.0575 |
Chi-Square Test Statistic,χ² = Σ(fo-fe)^2/fe
= 10.526
Level of Significance = 0.1
Number of Rows = 3
Number of Columns = 3
Degrees of Freedom=(#row - 1)(#column -1) = (3- 1 ) * ( 3-
1 ) = 4
p-Value = 0.0324417 [Excel
function: =CHISQ.DIST.RT(χ²,df) ]
Decision: p-value < α , Reject
Ho
conclusion: Best ski area is dependent on the level of the skier