In: Statistics and Probability
A survey of 1000 students found that 274 chose professional baseball team A as their favorite team. In a similar survey involving 760 students, 240 of them chose team A as their favorite. Compute a 95% confidence interval for the difference between the proportions of students favoring team A in the two surveys. Is there a significant difference?
Solution
p1=0.274
p2 = 0.316
n1=1000 n2 = 760
H0: p1 = p2
Ha: p1 not equals p2
Two tailed test for testing of proportions
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Variance of sample I = pq/n1 =
0.000216 Variance of sample II =
|
Pooled std deviation = 0.0219
Z statistic can be used as sample size is large
Z =
As |Z| = 1.92 <=1.96 at 95% level, H0 is accepted.
That is there is no significant difference between the two popul ations.