Retrospect

 

Study

Student ice cream preference

 

We chose to use a 2 proportion Z-test, we chose this becasuse we were looking for a difference in the proportions between males and females for ice cream preferance. We made the choice of vanilla as the respondants preferance a success and then compared the proportions resulting from this.

Hypothesis test:

1. p(1) is the proportion of people who prefer vanilla ice cream over chocolate ice cream. p(2) is the proportion of people who prefer chocolate ice cream over vanilla ice cream. p(1) - p(2) is the difference in proportion between males and females for ice cream preference.
2. H0 = p(1) - p(2) = 0
3. Ha = p(1) - P(2) ≠ 0
4. α = 0.05
5. Z = (p(1) - p(2) - hypothesized value) / √((s1)^2 / n(1)) + (s2)^2/ n(2))
6.Our data must be from a simple random sample. We have met this condition by taking a simple random sample from males and females at North Olmsted High School.
N*P and N*(1-P) must be larger than 5. This conditon is met because for men N*P = 37 * 0.540541 = 20.000017 and N * (1-P) = 37 * 0.459459 = 16.999983, and for women N * P = 36 * 0.444444 = 15.999984 and N * (1-P) = 36 * 0.666666 = 23.999976
Our Sample must be less than 10% of the population. This condition is met because our sample of 37 males is less than 10% of our population, male students at North Olmsted High school, and our other sample of 36 is also less than 10% of that population, Female students at North Olmsted High School.
7. z = .82
8. p = .409
9. Since our p value is .409 and .409 is greater than our significance level, .05 we fail to reject our null hypothesis that the true proportion of male ice cream preference for vanilla ice cream over chocolate does not differ from the female proportion of ice cream preference for vanilla over chocolate.