Economics 231 (Stats) Chapter 18 HW

A radio station wants to know if residents in their area are in favor of a proposed tax increase. They invite listeners to call in to respond to the poll. A total of 645 of the 800 who responded were against the tax. The station calculated a 95% confidenc

Because of the way the poll was conducted, the results are invalid.

Students at my university wanted to move spring break to later in the semester, so that weather at the beach would be warmer. They stood outside a campus dining hall and tried to flag down passersby to sign their petition. The student newspaper later anno

The sample wasn't random.

True or false? Sample size does not affect the results of a significance test.

False

What is the probability that we reject H0 when in fact H0 is TRUE?

the probability of a Type I error

What is the probability that we fail to reject H0 when in fact Halpha is TRUE?

the probability of a Type II error.

High power is desirable. What is the best way to increase the power of a test?

increase the sample size and increase alpha.

Suppose that the population of the scores of all high school seniors who took the SAT-V (SAT verbal) test this year follows a normal distribution with mean ? = 480 and standard deviation ? = 90. You read a report that claims that 10,000 students who took

find out the actual mean score of the 10,000 students.

A statistics instructor wants to know if an expensive computer program will help his students learn. He tries the program on a section of 35 students one semester and finds a P-value of 0.078 when comparing the class' average grade to that of the semester

The second class had more students � a larger sample size.