Chapter 8 Flashcards
(25 cards)
Which of the following best describes hypotheses?
a. Statements that are always true
b. Statements that cannot be tested
c. Statements about sample statistics
d. Statements about population parameters
d. Statements about population parameters
Which of the following does not describe the null hypothesis
a. A conservative statement about the population parameter
b. The research hypothesis
c. It is a status-quo, business-as-usual statement about the population parameter
d. All of the above statements describe the null hypothesis
b. The research hypothesis
In hypothesis testing, the null hypothesis is best described by which of the following statements?
a. The null hypothesis always gets the benefit of the doubt and is assumed to be true throughout the hypothesis testing procedure
b. The null hypothesis is always assumed to be false throughout the hypothesis testing procedure
a. The null hypothesis always gets the benefit of the doubt and is assumed to be true throughout the hypothesis testing procedure
The value in the null hypothesis comes from
a. The significance level of the hypothesis test
b. The sample statistic
c. The confidence level of the confidence interval
d. Assuming the status quo about the population
d. Assuming the status quo bout the population
What is the significance level of a test?
a. The probability that the null hypothesis is true
b. The probability of rejecting the null hypothesis when, in fact, the null hypothesis is true
c. The same as the population proportion
d. The probability of rejecting the null hypothesis hen, in fact, the null hypothesis is true
b. The probability of rejecting the null hypothesis when, in fact, the null hypothesis is true
A significance level that is often used in hypothesis testing by researchers and statisticians is ____
0.05
What is true in a hypothesis test, the farther the test statistic is from 0?
The more the null hypothesis is discredited
A small p-value does what?
a. It discredits the null hypothesis
b. It makes the hypothesis test inconclusive
c. It discredits the alternative hypothesis
a. It discredits the null hypothesis
The null hypothesis is always a statement about what?
a population parameter
A new drug is being tested to see whether it can reduce the chance of a heart attack in people who have previously had a heart attack. The rate of heart attack in the population of concern is 0.15. The null hypothesis is that p (the population proportion using the new drug that have a heart attack) is 0.15. What is the correct alternative hypothesis?
p < 0.15
Suppose an experiment is done with criminals released from prison in a certain state where the recidivism rate is 34%; that is, 34% of criminals return to prison within three years. One hundred random prisoners are made to attend a “boot camp” for two weeks before their release, and it is hoped that “boot camp” will have a good effect. The null hypothesis is that those attending boot camp have a recidivism rate of 34%, pequals0.34. Report the alternative hypothesis in words and in symbols.
Ha: p < 0.34
“the proportion of criminals who attend boot camp is less than 0.34”
A research hospital tries a new antibiotic scrub before surgery to see whether it can lower the rate of infections of surgical sites. The old rate of infection is 3.1%. The null hypothesis is that the proportion of infections is 0.031, p equals 0.031. Report the alternative hypothesis in words and in symbols.
p < 0.031, Ha
A magician claims that he can cause a coin to come up heads more than 50% of the time. A coin is flipped 50 times and 39 heads come up.
a. Null hypothesis:
b. Alternative hypothesis:
a. Ho: p = 0.50
b. Ha: p > 0.50
A friend is tested to see whether he can tell bottled water from tap water. There are 40 trials (half with bottled water and half with tap water), and he gets 22 right.
a. Determine the null hypothesis.
b. Determine the alternative hypothesis.
a. Ho: p = .50
b. Ha: p > 0.50
A researcher is testing someone who claims to have ESP by having that person predict whether a coin will come up heads or tails. The null hypothesis is that the person is guessing and does not have ESP, and the population proportion of success is 0.50. The researcher tests the claim with a hypothesis test, using a significance level of 0.05.
The probability of concluding that the person has ESP when in fact she or he does not have ESP is ____
0.05
Judging on the basis of experience, a politician claims that 56% of voters in a certain area have voted for an independent candidate in past elections. Suppose you surveyed 20 randomly selected people in that area, and 15 of them reported having voted for an independent candidate. The null hypothesis is that the overall proportion of voters in the area that have voted for an independent candidate is 56%. What value of the test statistic should you report?
The test statistic is z = 1.71
The symbol in the null hypothesis is _____
=
Which of the following steps is not included in preparing to do a hypothesis test?
a. Checking the sampling distribution conditions
b. Setting the significance level
c. Gathering data from multiple samples
d. Computing a test statistic
c. Gathering data from multiple samples
In hypothesis testing, what does an extreme value for the test statistic indicate?
a. The sample was not random
b. The null hypothesis is true
c. The null hypothesis is not true
d. The test was done incorrectly
d. The null hypothesis is not true
In hypothesis testing, what does a negative test statistic mean?
The sample proportion was less than the assumed population proportion in the null hypothesis
In hypothesis testing, when should the null hypothesis be rejected?
When the p-value is less than the significance level
A 2003 study of dreaming found that out of a random sample of 114 people, 89 reported dreaming in color. However, the rate of reported dreaming in color that was established in the 1940s was 0.25. Check to see whether the conditions for using a one-proportion z-test are met assuming the researcher wanted to test to see if the proportion dreaming in color had changed since the 1940s.
Are the conditions met?
Yes, all the conditions are met
A researcher carried out a hypothesis test using a two-tailed alternative hypothesis. Which of the following z-scores is associated with the smallest p-value? Explain.
z = -0.17 z = -1.64 z = -2.38 z = 2.86
z = 2.86
“the z-score farthest from 0 has the smallest tail area and thus has the smallest p-value”
T/F The z-value farthest from 0 has the smallest tail area and thus has the smallest p-value
True
