问题
单项选择题
Which of the following would result in a wider confidence interval（）
A. higher degree of confidence.
B. higher alpha level.
C. higher point estimate.
答案
参考答案：A
解析：
A higher degree of confidence (e. g. 99% instead of 95% ) would require a higher reliability factor (2.575 instead of 1.96 assuming a normal distribution). A wider confidence interval corresponds to a lower alpha significance level and the point estimate does not affect the width of the confidence interval.