Question

At a Clover City Council meeting, a plan to fund more sign language programs was presented. The reasoning behind the request was that less than 25% of parents with hearing-impaired children have the ability to pass a sign-language exam. If this is true, the council will agree to fund more programs for these parents. The council decides to take a 175-person volunteer sample of parents in Clover City that have children with auditory issues and conduct a significance test for H0: p = 0.25 and Ha: p < 0.25, where p is the proportion of these parents that can pass the sign language exam. They will perform the significance test at a significance level of α = 0.05 for the hypotheses.

Part A: Describe a Type II error that could occur. What impact could this error have on the situation? (3 points)

Part B: Out of the 175 volunteer parents of children with hearing problems, 54 passed, resulting in a p-value of 0.96. What can you conclude from this p-value given the data of the 175 parents is sufficient to perform a significance test for the hypotheses? (4 points)

Part C: What possible defect in the study can you find in Part B? Explain. (3 points)

Answer 1

Part A: A Type II error in this context is failing to reject the null hypothesis that 25% of parents with hearing impaired children have the ability to pass a sign-language exam when actually less than 25% are able to pass it.

Part B: We fail to reject the null hypothesis because the p-value of 0.96 is larger than α = 0.05. The evidence is not substantial that the proportion of parents with hearing impaired children in Clover City who are able to pass a sign language exam is less than 0.25. The sample proportion of phat = 0.96 is greater than 0.25.

Part C: The sample of 175 parents with hearing impaired children in Clover City was a group of volunteers, so most likely they were confident in their ability to pass a sign language exam which could better the chances of more passing sign language exams.