07 Jan State the null hypothesis

Week 5 discussion

MAT2058 Discussion Questions

Week 5

Text:

Textbook: Triola, M. F. (2014). Elementary statistics technology update (12th ed.). Boston, MA: Pearson Education.

Instructions:

• In the Course Home announcement area there should be a listing with your name and letter assigned for the discussion questions. If there is not such a list, then find the first letter of your last name below, and complete the two discussion problems associated with this letter.

• Please show all of the steps and processes you used to solve each of the problems.

• Remember to do both of the problems assigned and to respond to two of your classmates’ solutions.

• Please try to respond to two of your classmates who have had very different problems than yours assigned to them. You should receive more credit for doing so.

• In responding to the postings of at least two of your classmates, you can

o ask a question about your classmate’s solution(s)

o offer help when you see an error, or

o seek help in completing your own problems.

Remember that non-substantive posts such as “Good job!” will not count toward your participation score. Again, try to respond to at least two classmates who have problems assigned that are quite different from yours.

Please note that the assigned problems vary in difficulty and the list has been randomly generated for each of the two assigned problems.

Revised Week 5 Discussion Questions

See the first instruction on

the previous page.

Please submit the two discussion items for your assigned letter.

Describe what a type I and type II error When a parachute is inspected, the inspector is

would be for the following null hypothesis: looking for anything that might indicate the parachute

A : Most environmental crises in this and might not open.

decade were man-made. – State the null and alternative hypotheses.

What is the alternative hypothesis for a null State the null and alternative hypotheses for the

following:

hypothesis stating that the average time a

B and

person keeps a cell phone is at most three

– You are investigating a complaint that “special

years?

delivery mail takes too much time” to be delivered.

State the null and alternative hypotheses for the

following:

C What would be a Type II Error for: and

HO: µ ? 3 years? – You want to show that people find the new design

for a recliner chair more comfortable than the old

design.

Answer “True” if the statement is always true. If the

statement is not always true, replace the underlined

What is the mathematical relationship words with words that make the statement always

true.

D between the ? level and the confidence level and

of a hypothesis test? The risk of making a type I error is directly

controlled in a hypothesis test by establishing a level

for ?.

Describe what a Type I and Type II error State the null and alternative hypotheses for the

would be for the following null hypothesis: following:

E and

: Lipitor is not considered to be a

– You are testing a new formula for hair conditioner

calcium blocker. and hope to show that it is effective on “split ends.”

Answer “True” if the statement is always true. If the

Describe what a type I and type II error statement is not always true, replace the underlined

would be for the following null hypothesis: words with words that make the statement always

F and true.

H_0: There is no difference between steam

and chemical carpet cleaning methods. Failing to reject the null hypothesis when it is false

is a correct decision.

When a medic at the scene of a serious accident

Describe what a Type I and Type II error inspects each victim, she administers the appropriate

medical assistance to all victims, unless she is

G would be for the following null hypothesis: and certain the victim is dead.

: There is no difference between

– Describe the four possible outcomes that can result

chemotherapy and radiation treatments.

depending on the truth of the null hypothesis and the

decision reached.

State the null and alternative hypotheses for the

What is the relationship between the following:

H and

Confidence Level and Type I Error?

– You are trying to show that music lessons have a

positive effect on a child’s self-esteem.

Answer “True” if the statement is always true. If the

statement is not always true, replace the underlined

As type I error increases, type II error words with words that make the statement always

I and true.

decreases. T or F, and why or why not?

Rejection of a null hypothesis that is false is a Type

II error.

A) Give an example of a Null Hypothesis The director of an advertising agency is concerned

that might be made in your line of work. with the effectiveness of a television commercial.

J B) Referring to this Null Hypothesis, please and – What null hypothesis is she testing if she commits

describe what would constitute a Type II a type I error when she erroneously says that the

Error? commercial is effective?

The director of an advertising agency is concerned

What critical value for z would be used to with the effectiveness of a television commercial.

K test the hypotheses: versus and – What null hypothesis is she testing if she makes a

, for ? = 0.01 ?

correct decision when she says that the commercial is

not effective?

A politician is concerned with winning an upcoming

Give an example of a hypothesis where a election.

L Type I Error would be more critical if made and

than a Type II Error and explain why you – What null hypothesis is he testing if he commits a

feel this way. Type I error when he says that he will win the

election?

State the null hypothesis Ho and the alternative

What critical region(s) for z would be used hypothesis Ha that would be used for a hypothesis test

of the following:

M to test the hypotheses: versus and

, for ? = 0.05 ? The mean age of the students enrolled in evening

classes at a certain college is greater than 26 years.

State the null hypothesis Ho and the alternative

What critical region(s) for z would be used hypothesis Ha that would be used for a hypothesis test

of the following:

N to test the hypotheses: and and

, for ? = 0.01 ? The mean weight of packages shipped on Air Express

during the past month was less than 36.7 lb.

Answer “True” if the statement is always true. If the

statement is not always true, replace the underlined

Write a correct alternative hypothesis for: words with words that make the statement always

O and true.

Ho: µ ? 35.

1 ? ? is known as the level of significance of a

hypothesis test.

Answer “True” if the statement is always true. If the

statement is not always true, replace the underlined

Write a correct alternative hypothesis for the words with words that make the statement always

true.

P claim that the average professional and

basketball player is at least 6’ 9” tall. Alpha is the measure of the area under the curve of

the standard score that lies in the rejection region for

Ho.

Rejecting the null hypothesis when it is false The calculated p-value for a hypothesis test is 0.084.

Q What decision about the null hypothesis would

is a Type I Error. T or F, and why or why and occur in the following:

not? The hypothesis test is completed at the 0.10 level of

significance.

R What is the relationship between ? and and What decision is reached when the p-value is greater

Type I Error? than ??

The calculated p-value for a hypothesis test is 0.084.

In hypothesis testing, as the ? level gets What decision about the null hypothesis would

S smaller, the level of confidence increases. T and

occur in the following:

or F, and why or why not?

The hypothesis test is completed at the 0.05 level of

significance.

T Critical regions get larger as ? values get and What decision is reached when ? is greater than the p-

smaller. T or F, and why or why not? value? Why is this decision reached?

A) Give an example of a Null Hypothesis State the null and alternative hypotheses for the

that might be made in your line of work.

following:

U B) Referring to this Null Hypothesis, please and

– You are trying to show that cigarette smoke affects

describe what would constitute a Type I

the quality of a person’s life.

Error.

State the null and alternative hypotheses for the

What critical value for z would be used to following:

V test the hypotheses: and and – You want to show an increase in buying and

, for ? = 0.05 ?

selling of single-family homes this year when

compared with last year’s rate.

When a parachute is inspected, the inspector is

If the critical values of a hypothesis test are looking for anything that might indicate the parachute

might not open.

W +2.58 and -2.58, what would be the critical and

regions? – State the null and alternative hypotheses for this

situation.

X If ? = 0.10, what is the confidence level of a and Based on the ? level of the question to the left, what

statistical test? critical value is used to form the confidence interval?

State the null hypothesis Ho and the alternative

Give an example of a hypothesis where a hypothesis Ha that would be used for a hypothesis test

Y Type II Error would be more critical if made and of the following:

than a Type I Error and explain why you feel

this way. The mean life of fluorescent light bulbs is at least

1600 hours.

State the null hypothesis Ho and the alternative

hypothesis Ha that would be used for a hypothesis test

of the following:

Failing to reject the null hypothesis when it

Z is false is a Type II Error. T or F, and why and The mean strength of welds by a new process is

or why not? different from 570 lb per unit area, the mean strength

of welds by the old process.