Chapter 9

Which of the following are one-tailed tests?

HO: u < (or equal) 10 HA: u > 10 HO: u >(or equal) 400 HA: u < 400

What is the decision rule when using the p-value approach to hypothesis testing?

Reject H0 if the p-value < α.

If the p-value for a hypothesis test is 0.027 and the chosen level of significance is a=.05, then the correct conclusion is to

Reject the null hypothesis

A type I error occurs when we

Reject the null hypothesis when it is actually true.

If the chosen significance level is a=.05, then

There is a 5% probability of rejecting a true null hypothesis

A hypothesis test regarding the population mean u is based on the sampling distribution of the sample mean (x bar).

True

A type I error is committed when we reject the null hypothesis which is actually true.

True

As a general guideline, we use the alternative hyp. as a vehicle to establish something new, or contest the status quo, for which a corrective action may be required.

True

A hypothesis test regarding the population mean is based on

the sampling distribution of the sample mean

For any given sample size,

Decreasing the prob. of a type I error (alpha a) will increase the prob. of a Type II error (beta)

A type II error occurs when we

Do not reject the null hypothesis when it is actually false.

When we reject the null hypothesis when it is actually false we have committed

No error.

If the p-value for a hypothesis test is 0.07 and the chosen level of significance is a=.05, then the correct conclusion is to

Not reject the null hypothesis

For any given sample size, any attempt to reduce the likelihood of making one type of error (type I or II) will increase the likelihood of the other error.

True

A two-tailed hypothesis test of the population mean or population proportion has

Two critical values, one positive and one negative

The null hypothesis test in a hypothis test refers to

the default state of nature

A local courier service advertises that its average delivery time is less than 6 hours for local deliveries. When testing the two hypotheses, u stands for?

the mean delivery time

A type II error is made when we reject the null hypothesis and the null hypothesis is actually false.

False

If the null hypothesis is rejected at a 1% significance level, then

The null hypothesis will be rejected at a 5% significance level

In a one-tailed test, the rejection region is located under one tail (left or right) of the corresponding prob. distribution, while in a two- tailed test the region is located under both tails.

True

The null hypothesis typically corresponds to a presumed default state of nature.

True

Under the assumption that the null hyp. is true as an equality, the p-value is the likelihood of observing a sample mean that is at least as extreme as the one derived from the given sample.

True

A statistics professor works tirelessly to catch students cheating on his exams. He has particular routes for teaching assistants to patrol, an elevated chair to ensure an unobstructed view of all his students, and even a video recording of the exam in case additional evidence needs to be collected. He estimates that he catches 95% of students who cheat in his class, but 1% of the time he accuses a student of cheating and he is actually correct. Consider the null hypothesis, "the student is not cheating." What is the prob. of a type 1 error?

Type 1: 1%

A one-tailed hypothesis test of the population mean has

Only one critical value

When conducting a hypothesis test for a given sample size, if the probability of a Type I error decreases, then the

Probability of incorrectly accepting the null increases

Which of the following answers represents the objective of a hypothesis test?

Rejecting the null hypothesis when it is false not rejecting the null hypothesis when it is true

When conducting a hypothesis test which of the following decisions represents an error?

Rejecting the null hypothesis when its is true.

A professional sports organization is going to implement a test for steroids. The test is gives a positive reaction in 94% of the people who have taken the steroid. However, it erroneously gives a positive reaction in 4% of the people who have not taken the steriod. What is the probability of a type I and type II error using the null hypothesis "the individual has not taken the steroids"

Type I- 4% Type II- 6%

Which of the following types of test may be preformed?

right-tailed, left-tailed, two-tailed

The alt. hypothesis typically agrees with the status quo.

False

The critical value approach specifies a range of values, also called the rejection region, such that if the value of the test statistic falls into this range, we do not reject the null hypothesis.

False

In general, the null and alt hypothesis are

mutually exclusive

A fast-food franchise is considering building a restaurant at a busy intersection. A financial advisor determines that the site is acceptable if, on average, more than 300 automobiles pass the location per hour. The advisor tests the following hypotheses: HO: u < (or equal) 300 HA: u > 300 -The consequences of committing a type I error would be that -The consequences of committing a type I error would be that -u stands for

-The franchiser builds on an unacceptable site. -The franchiser does not build on an acceptable site - The average number of automobiles that pass the intersection per hour

When conducting a hypothesis test for a given sample size, if a is increased from 0.05 to 0.10, then

-The probability of incorrectly rejecting the null increases -The probability of incorrectly failing to reject the null decreases -The probability of Type II error decreases

It is generally believed that no more than .5 of all babies in a town in Texs are born out of wedlock. a politician claims that the proportion of babies that are born out of wedlock is increasing. -define the population parameter of interest -p stands for? - identify the null and alt. hypothesis

-the current proportion of babies born out of wedlock -the current proportion of babies born out of wedlock -Ho: p (< or equal) .50 HA: p > .50

Consider the following competing hypotheses: . The value of the test statistic HO: u = 0 HA: u (does not equal) 0 is z = -1.38. If we choose a 5% significance level, then we .

Do not reject the null hypothesis and conclude that the population mean is not significantly different from 0.

On the basis of sample information, we either "accept the null hypothesis" or "reject the null hypothesis".

False

Many cities around the US are installing LED lights, in part to combat crime by improving visibility after dusk. An urban department claims that the proportion of crimes committed after dark will fall below the current level of .84 if LED lights are installed. Specify the null and alt hyp. to test the police department's claim.

HO: p > (or equal) .84 HA: p < .84

Which of the following are two-tailed tests?

HO: u = 10 HA: u (does not equal) 10

The national average for an 8th grade reading comprehension test is 73. A school district claims that its 8th graders outperform the national average. In testing the school district's claim, how does one define the population parameter of interest?

The mean score on the 8th grade reading comprehension test.

Consider the following hypotheses that relate to the medical field: HO: A person is free of disease. HA: A person has disease. In this instance a type I error In this instance, a type II error is often referred to as

a false negative

Consider the following hypotheses that relate to the medical field: HO: A person is free of disease. HA: A person has disease. In this instance, a type I error is often referred to as

a false positive

The alt. hypothesis typically

contests the status quo for which a corrective action may be required