Learning Materials
Features
Discover
Chapter 11: Q. 3.3 (page 705)
What conclusion would you draw? Justify your answer.
At significance level, there is enough evidence to state that there is a difference in the distribution of users in both the schools.
Over 30 million students worldwide already upgrade their learning with 91影视!
All the tools & learning materials you need for study success - in one app.
Get started for free
Who were the popular kids at your elementary school? Did they get good grades or have good looks? Were they good at sports? A study was performed to examine the factors that determine social status for children in grades , and . Researchers administered a questionnaire to a random sample of students in these grades. One of the questions they asked was 鈥淲hat would you most like to do at school: make good grades, be good at sports, or be popular?鈥� The two-way table below summarizes the students鈥� responses.
(a) Construct an appropriate graph to compare male and female responses. Write a few sentences describing the relationship between gender and goals.
(b) Is there convincing evidence of an association between gender and goals for elementary school students? Carry out a test at the localid="1653534557186" level and report your conclusion.
(c) Which cell contributes most to the chi-square statistic in part (b)? Explain
Benford鈥檚 lawFaked numbers in tax returns, invoices, or expense account claims often display patterns that aren鈥檛 present in legitimate records. Some patterns are obvious and easily avoided by a clever crook. Others are more subtle. It is a striking fact that the 铿乺st digits of numbers in legitimate records often follow a model known as Benford鈥檚 law. Call the 铿乺st digit of a randomly chosen record X for short. Benford鈥檚 law gives this probability model for X (note that a 铿乺st digit can鈥檛 be 0):
A forensic accountant who is familiar with Benford鈥檚 law inspects a random sample of invoices from a company that is accused of committing fraud. The table below displays the sample data.
(a) Are these data inconsistent with Benford鈥檚 law? Carry out an appropriate test at the level to support your answer. If you 铿乶d a signi铿乧ant result, perform follow-up analysis.
(b) Describe a Type I error and a Type II error in this setting, and give a possible consequence of each. Which do you think is more serious?
Representative sample? For a class project, a group of statistics students is required to take an SRS of students from their large high school to take part in a survey. The students鈥� sample consists of freshmen, sophomores, juniors, and seniors. The school roster shows that of the students enrolled at the school are freshmen, are sophomores, are juniors, and are seniors.
(a) Construct a well-labeled bar graph that shows the distribution of grade levels (in percents) for the sample data. Do these data give you any reason to suspect that the statistics students鈥� sample is unusual? Explain. (b) Use an appropriate test to determine whether the sample data differ significantly from the actual distribution of students by grade level at the school.
A survey by the National Institutes of Health asked a random sample of young adults (aged 19 to 25 years), 鈥淲here do you live now? That is, where do you stay most often?鈥� Here is the full two-way table (omitting a few who refused to answer and one who claimed to be homeless):
a) Should we use a chi-square test for homogeneity or a chi-square test of association/independence in this setting? Justify your answer.
(b) State appropriate hypotheses for performing the type of test you chose in part (a). Minitab output from a chi-square test is shown below
(c) Check that the conditions for carrying out the test are met.
(d) Interpret the P-value in context. What conclusion would you draw?
Regulating guns The National Gun Policy Survey asked a random sample of adults, 鈥淒o you think there should be a law that would ban possession of handguns except for the police and other authorized persons?鈥� Here are the responses, broken down by the respondent鈥檚 level of education:
(a) How do opinions about banning handgun ownership seem to be related to the level of education? Make an appropriate graph to display this relationship. Describe what you see.
(b) Determine whether or not the sample provides convincing evidence that education level and opinion about a handgun ban are independent in the adult population
What do you think about this solution?
We value your feedback to improve our textbook solutions.
Explanations 
Textbooks 
Flashcards 
91影视 AI 
Notes 
Study Plans 
Study Sets 
Find a degree 
Magazine