In: Statistics and Probability
9. A soft drink company is interested in knowing whether there is a relationship between cola preference and age. A random sample of 800 people is chosen for a taste test. The results of the study are found in the following table. Is there sufficient evidence at the 0.005 level of significance to lead you to believe that there is an association between cola preference and age? *You can use your test value or the p-value to decide. Cola A Cola B Cola C 15-29 94 102 105 30-44 99 97 86 45-59 68 73 76 State the Hyp: Test Value is_____=______ P-value = ________ Decision:__________________________________________________ Conclusion:_______________________________________
Ho: given two variable are independent |
H1: Given two variables are not independent |
Observed Frequencies | |||||||
0 | |||||||
0 | 15-29 | 30-44 | 45-59 | Total | |||
cola A | 94 | 99 | 68 | 261 | |||
cola B | 102 | 97 | 73 | 272 | |||
cola C | 105 | 86 | 76 | 267 | |||
Total | 301 | 282 | 217 | 800 | |||
Expected frequency of a cell = sum of row*sum of column / total sum | |||||||
Expected Frequencies | |||||||
15-29 | 30-44 | 45-59 | Total | ||||
cola A | 301*261/800=98.201 | 282*261/800=92.003 | 217*261/800=70.796 | 261 | |||
cola B | 301*272/800=102.34 | 282*272/800=95.88 | 217*272/800=73.78 | 272 | |||
cola C | 301*267/800=100.459 | 282*267/800=94.118 | 217*267/800=72.424 | 267 | |||
Total | 301 | 282 | 217 | 800 | |||
(fo-fe)^2/fe | |||||||
cola A | 0.180 | 0.532 | 0.110 | ||||
cola B | 0.001 | 0.013 | 0.008 | ||||
cola C | 0.2053 | 0.7001 | 0.1766 |
Chi-Square Test Statistic,χ² = Σ(fo-fe)^2/fe
= 1.927
Level of Significance = 0.005
Number of Rows = 3
Number of Columns = 3
Degrees of Freedom=(#row - 1)(#column -1) = (3- 1 ) * ( 3- 1 )
= 4
p-Value = 0.7492 [Excel function:
=CHISQ.DIST.RT(χ²,df) ]
Decision: p value > α , do not reject
Ho
there is not an association between cola preference and age
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