In: Statistics and Probability
A hospital director is told that 32% of the treated patients are uninsured. The director wants to test the claim that the percentage of uninsured patients is below the expected percentage. A sample of 160 patients found that 40 were uninsured. At the 0.05 level, is there enough evidence to support the director's claim?
Solution :
Given that,
= 0.32
1 - = 0.68
n = 160
x = 40
Level of significance = = 0.05
Point estimate = sample proportion = = x / n = 0.25
This a right (One) tailed test.
Ho: p = 0.32
Ha: p < 0.32
Test statistics
z = ( - ) / *(1-) / n
= ( 0.25 - 0.32) / (0.32*0.68) / 160
= -1.90
P-value = P(Z<z)
= P(Z < -1.90)
= 0.0287
The p-value is p = 0.0287, and since p = 0.0287 < 0.05, it is concluded that the null hypothesis is rejected.
Conclusion:
It is concluded that the null hypothesis Ho is rejected. Therefore, there is enough evidence to claim that the percentage of
uninsured patients is below the expected percentage 32%, at the 0.05 level of significance.