In: Statistics and Probability
A department store, A, has four competitors: B,C,D, and E. Store A hires a consultant to determine if the percentage of shoppers who prefer each of the five stores is the same. A survey of 1100 randomly selected shoppers is conducted, and the results
about which one of the stores shoppers prefer are below. Is there enough evidence using a
significance level α = 0.05 to conclude that the proportions are really the same?
Answer:-
Given That:-
A department store, A, has four competitors: B,C,D, and E. Store A hires a consultant to determine if the percentage of shoppers who prefer each of the five stores is the same. A survey of 1100 randomly selected shoppers is conducted, and the results about which one of the stores shoppers prefer are below. Is there enough evidence using a significance level α = 0.05 to conclude that the proportions are really the same?
Given,
(i) The null hypothesis :
The population frequencies are equal to the expected frequencies (to be calculated below).
(ii) The alternative hypothesis :
The null hypothesis is false.
(iii)
(iv) The degrees of freedom:
k - 1 = 5 -1
= 4
(v) The test statistic can be calculated using a table:
Peference | % of Shoppers | E | O | O - E | ||
A | 20% | 0.2 * 1100 = 220 | 262 | 42 | 1764 | 8.018 |
B | 20% | 0.2 * 1100 = 220 | 234 | 14 | 196 | 0.891 |
C | 20% | 0.2 * 1100 = 220 | 204 | -16 | 256 | 1.163 |
D | 20% | 0.2 * 1100 = 220 | 190 | -30 | 900 | 4.091 |
E | 20% | 0.2 * 1100 = 220 | 210 | -10 | 100 | 0.455 |
= 14.618
(vi) From and k - 1 = 4
The critical value is 9.488.
(vii) Is there enough evidence to reject ?
Since , there is enough statistical evidence to reject to reject the null hypothesis and to believe that customers do not prefer each of the five stores equally.
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