Question

A study by Allstate Insurance Co. finds that 82% of teenagers have used cell phones while driving (The Wall Street Journal, May 5, 2010). In October 2010, Massachusetts enacted a law that forbids cell phone use by drivers under the age of 18. A policy analyst would like to determine whether the law has decreased the proportion of drivers under the age of 18 who use a cell phone.

which one is correct H0 and H1 statement?

	a.	H0: proportion of teenagers who used cell phones while driving = 0.82 H1: proportion of teenagers who used cell phones while driving  ≠ 0.82
	b.	H0: proportion of teenagers who used cell phones while driving < 0.82 H1: proportion of teenagers who used cell phones while driving  = 0.82
	c.	H0: proportion of teenagers who used cell phones while driving = 0.82 H1: proportion of teenagers who used cell phones while driving < 0.82
	d.	H0: proportion of teenagers who used cell phones while driving = 0.82 H1: proportion of teenagers who used cell phones while driving > 0.82

Which one is correct statement? Choose all applied.

	a.	How to choose a level of alpha should be based on sampling error.
	b.	Person who select the value of alpha is a person who does the test.
	c.	Definition of p-value is that when the null statement is true, it is probability that test statistics would take a value as actually observed or more extreme than actually observed
	d.	Critical value approach and p-value approach do not give us same conclusion all the time.

Answer 1

Here we want to test whether the proportion of teenagers who used cell phone while driving has decreased from 0.82 after the law .

Let p be the proportion .

Then our Hypotheses will be

Ho : p = 0.82 vs H1 : p< 0.82

C.H0 : Proportion of teenagers who used cell phones while driving = 0.82

H1 : proportion of teenagers who used cell phones while driving < 0.82

In Hypothesis testing the researcher who is performing the test determines that what will be the level of significance . That means what percentage of type 1 error will he allow.

So statement (b) is correct .

And the p Value means probability of obtaining a test statictic as observed or more extreme than the observed value when the Null hypothesis is true .

So statement (c) is correct .