Week 5 Part B: Quizzes
Suppose you conduct a significance test for the population proportion and your p-value is 0.184. Given a 0.10 level of significance, which of the following should be your decision? Group of answer choices
.184 > .10 (If the p is high, the null will fly) - but we never "accept" the null, we only fail to reject. fail to reject null
A manufacturer finds that in a random sample of 100 of its CD players, 96% have no defects. The manufacturer wishes to make a statement about the percentage of non-defective CD players and is prepared to exaggerate.
1 prop z CI
A manufacturer considers his production process to be out of control when defects exceed 3%. In a random sample of 85 items, the defect rate is 5.9% but the manager says that this is only a sample fluctuation and production is not really out of control. At the 0.01 level of significance, test the manager's statement.
1 prop z HT
A poll of 1068 adult Americans reveals that 48% of the voters surveyed prefer the Democratic candidate for the presidency. At the 0.05 level of significance, we wish to show that at least half of all voters prefer the Democrat.
1 prop z HT
An article in a journal reports that 34% of American fathers take no responsibility for child care. A researcher states that the figure is higher for fathers in the town of Littleton. A random sample of 234 fathers from Littleton yielded 96 who did not help with child care. Test the researcher's statement at the 0.05 significance level.
1 prop z HT
A laboratory tested twelve chicken eggs and found that the mean amount of cholesterol was 185 milligrams with s = 17.6 milligrams. Estimate the true mean cholesterol content of all such eggs.
1 sample t mean CI
A sociologist develops a test to measure attitudes towards public transportation, and 27 randomly selected subjects are given the test. Their mean score is 76.2 and their standard deviation is 21.4. Estimate the mean score of all such subjects.
1 sample t mean CI
Thirty randomly selected students took the calculus final. If the sample mean was 95 and the standard deviation was 6.6, estimate the mean score of all students.
1 sample t mean CI
A simple random sample of 15-year old boys from one city is obtained and their weights (in pounds) are listed below. Use a 0.01 significance level to test that these sample weights come from a population with a mean equal to 147 lb. 146 140 160 151 134 189 157 144 175 127 164
1 sample t mean HT
The maximum acceptable level of a certain toxic chemical in vegetables has been set at 0.4 parts per million (ppm). A consumer health group measured the level of the chemical in a random sample of tomatoes obtained from one producer. The levels, in ppm, are shown below. 0.31 0.47 0.19 0.72 0.56 0.91 0.29 0.83 0.49 0.28 0.31 0.46 0.25 0.34 0.17 0.58 0.19 0.26 0.47 0.81 Do the data provide sufficient evidence to support that the mean level of the chemical in tomatoes from this producer is greater than the recommended level of 0.4 ppm?
1 sample t mean HT
If a two-sided null hypothesis can not be rejected for a single mean at a given significance level, then the corresponding one-sided null hypothesis (i.e., the same sample size, the same standard deviation, and the same mean) will_________ be rejected at the same significance level.
Sometimes
For a given hypothesis test, if we do not reject the null, and null is true.
no error has been committed
When are p-values negative?
ince probabilities are NEVER negative, the p-value is NEVER negative. the p -value is never negative
A nationwide study of American homeowners revealed that 64% have one or more lawn mowers. A lawn equipment manufacturer, located in Omaha, feels the estimate is too low for households in Omaha.
??? NOT: 1 Prop Z HT, 2 Prop Z HT, or 2 Prop C CI
In a hypothesis test, the probability of obtaining a value of the test statistic equal to or even more extreme than the value observed - given the null hypothesis is true - is referred to as:
A Type I error is the mistake of rejecting the null hypothesis when it is actually true. A type II error is the mistake of failing to reject the null hypothesis when it is actually false. Correct Answer: ??? Wrong Answer: Type I Error
The mean resting pulse rate for men is 72 beats per minute. A simple random sample of men who regularly work out at Mitch's Gym is obtained and their resting pulse rates (in beats per minute) are listed below. Use a 0.05 significance level to test that that these sample pulse rates come from a population with a mean less than 72 beats per minute. 54 59 69 84 74 64 69 70 66 80 59 71 76 63
1 sample t mean HT
In a random sample of 300 women, 45% favored stricter gun control legislation. In a random sample of 200 men, 25% favored stricter gun control legislation. Estimate the difference between men and women in general.
2 prop z CI
In a random sample of 500 people aged 20-24, 22% were smokers. In a random sample of 450 people aged 25-29, 14% were smokers. Estimate the difference between the the two age groups.
2 prop z CI
A researcher finds that of 1000 people who said that they attend a religious service at least once a week, 31 stopped to help a person with car trouble. Of 1200 people interviewed who had not attended a religious service at least once a month, 22 stopped to help a person with car trouble. At the 0.05 significance level, we wish to show that the two proportions are not equal.
2 prop z HT
In a random sample of 360 women, 65% favored stricter gun control laws. In a random sample of 220 men, 60% favored stricter gun control laws. We wish to show that the proportion of women favoring stricter gun control is higher than the proportion of men favoring stricter gun control.
2 prop z HT
In a random sample of 500 people aged 20-24, 22% were smokers. In a random sample of 450 people aged 25-29, 14% were smokers. Test that that the proportion of smokers in the two age groups is the same. Use a significance level of 0.01.
2 prop z HT
A certain brand of jelly beans are made so that each package contains about the same number of beans. The filling procedure is not perfect, however. The packages are filled with a presumed average of 375 jelly beans with the number going into each bag is normally distributed with a standard deviation of 8. Yesterday, Jane went to the store and purchased four of these packages in preparation for a Spring party. Jane was curious, and she counted the number of jelly beans in these packages - her four bags contained an average of 382 jelly beans. In the above scenario, which of the following is a parameter?
375 is the assumed null. 382 is the sample data. The true average is unknown. The average number of jelly beans in all packages made, which is unknown.
The _________ states the means are ________ for a one tailed test.
A one-tailed test is a statistical test in which the critical area of a distribution is one-sided so that it is either greater than or less than a certain value, but not both. null hypothesis; equal
A sampling distribution is
A sampling distribution shows every possible result a statistic can take in every possible sample from a population and how often each result happens. (Khan Academy) Correct Answer: ??? Wrong Answer: All of the answers are correct
If a two-sided null hypothesis is rejected for a single mean at a given significance level, the corresponding one- sided null hypothesis (i.e., the same sample size, the same standard deviation, and the same mean) will_________ be rejected at the same significance level.
Always
If a null hypothesis is not rejected at a significance level of .05, it will ______ be rejected at a significance level of .01
CORRECT: ?? Never?? WRONG: Sometimes If the null hypothesis is rejected at the 0.01 significance level, it will always be rejected at the 0.05 significance level. Equivalently, if the null hypothesis is not rejected at the 0.05 significance level, it cannot be rejected at the 0.05 significance level. If it is not rejected at 0.01, it still could be rejected at 0.05. (Quora)
If a null hypothesis is rejected at a significance level of .05, it will ______ be rejected at a significance level of .01
CORRECT: ?? Sometimes?? WRONG: Always If the null hypothesis is rejected at the 0.01 significance level, it will always be rejected at the 0.05 significance level. Equivalently, if the null hypothesis is not rejected at the 0.05 significance level, it cannot be rejected at the 0.05 significance level. If it is not rejected at 0.01, it still could be rejected at 0.05. (Quora)
If a null hypothesis is rejected at a significance level of .01, it will ______ be rejected at a significance level of .05
Correct: ?? Always?? WRONG: Sometimes If the null hypothesis is rejected at the 0.01 significance level, it will always be rejected at the 0.05 significance level. Equivalently, if the null hypothesis is not rejected at the 0.05 significance level, it cannot be rejected at the 0.05 significance level. If it is not rejected at 0.01, it still could be rejected at 0.05. (Quora)
Which statement is incorrect?
If we fail to reject the null hypothesis, then it is proven that null hypothesis is true.
Five students took a math test before and after tutoring. Their scores were as follows. Subject A B C D E Before 71 66 67 77 75 After 75 75 65 80 87 The researcher wants to show that tutoring improves math scores.
Paired mean t test
Researchers are concerned about the impact of students working while they are enrolled in classes, and they'd like to know if students work too much and therefore are spending less time on their classes than they should be. First, the researchers need to find out, on average, how many hours a week students are working. They know from previous studies that the standard deviation of this variable is about 5 hours. Suppose that this confidence interval was (6.82, 7.38). Which of these is a valid interpretation of this confidence interval?
We are 95% confident that the average number of hours worked by all UF students is between 6.82 and 7.38 hours