Questions and Answers of Intro Stats

The Pew Research Center conducts surveys regularly asking respondents which political party they identify with or lean toward. Among their results is the following table relating preferred political
Babe Ruth was the first great “slugger” in baseball. His record of 60 home runs in one season held for 34 years until Roger Maris hit 61 in 1961. Mark McGwire (with the aid of steroids) set a new
Researchers for the Herbal Medicine Council collected information on people’s experiences with a new herbal remedy for colds. They went to a store that sold natural health products. There they
Consider again the data on birth order and college majors in Exercise R1.28.a) What is the marginal distribution of majors?b) What is the conditional distribution of majors for the oldest children?c)
According to the Bureau of Labor Statistics, the mean hourly wage for Chief Executives in 2009 was $80.43 and the median hourly wage was $77.27. By contrast, for General and Operations Managers, the
Consider again the Pew Research Center results on age and political party in Exercise R1.33.a) What is the marginal distribution of party affiliation?b) Create segmented bar graphs displaying the
The Bicycle Helmet Safety Institute website includes a report on the number of bicycle fatalities per year in the United States. The table below shows the counts for the years 1994–2015.a) What are
Here is a stem-and-leaf display showing profits (in $M) for 30 of the 500 largest global corporations (as measured by revenue). The stems are split; each stem represents a span of 5000 ($M), from a
Later on, the forester in Exercise 39 shows you a histogram of the tree diameters he used in analyzing the woods that was for sale. Do you think he was justified in using a Normal model?Data From
For the car speed data in Exercise 30, here are the histogram, boxplot, and Normal probability plot of the 100 readings. Do you think it is appropriate to apply a Normal model here? Explain.Data From
A company that markets buildit- yourself furniture sells a computer desk that is advertised with the claim “less than an hour to assemble.” However, through post purchase surveys the company has
Exercise 10 proposes modeling IQ scores with N(100, 15). What IQ would you consider to be unusually high?Data From Exercise 10Some IQ tests are standardized to a Normal model, with a mean of 100 and
Consumer groups are concerned that cereals with a high sugar content (usually designed for children) are placed just where kids are most likely to see them—in the middle shelf of the supermarket.
Is the mean amount of salt higher in menu items that contain meat?a) Compare the sodium content of the meat and non-meat items with displays and summary statistics.b) By shuffling the variable Meat
Thirty-four men completed the men’s alpine downhill part of the super combined. The gold medal winner finished in 114.9 seconds. Here are the times (in seconds) for all competitors.a) The mean time
The Hopkins Forest data set includes all 24 weather variables reported by the researchers. Many of the variables (e.g., temperature, relative humidity, solar radiation, wind) are reported as daily
NFL data from the 2015 football season reported the number of yards gained by each of the league’s 488 receivers:The mean is 274.73 yards, with a standard deviation of 327.32 yards.a) According to
Suppose we take logarithms of the CEO compensations in Exercise 47. The histogram of log Compensation looks like this:with a mean of 1.07 and a standard deviation of 0.26.a) According to the Normal
The Titanic data set includes more variables than just those discussed in Chapter 2. Others include the crew’s job and where each person boarded the ship. Stories, biographies and pictures can be
The Glassdoor Economic Research Blog published the compensation (in millions of dollars) for the CEOs of large companies. The distribution looks like this:The mean CEO compensation is $14.1M and the
In a study of streams in the Adirondack Mountains, the following relationship was found between the water’s pH and its hardness (measured in grains):Is it appropriate to summarize the strength of
The Student Survey data set introduced in the Chapter 3 exercises includes responses to 13 questions. Investigate the associations among the variables that you find interesting. Write a short report
A study examined brain size (measured as pixels counted in a digitized magnetic resonance image [MRI] of a cross section of the brain) and IQ (4 performance scales of the Wechsler IQ test) for
The data set Movies 06-15 introduced in the Chapter 3 exercises includes the distributor, number of tickets sold, and gross revenue in addition to the MPAA rating and the genre for each of the 10
A study of traffic delays in 68 U.S. cities found the following relationship between Total Delay (in total hours lost) and Mean Highway Speed:Is it appropriate to summarize the strength of
Consider the IQ model N(100, 15) one last time.a) What IQ represents the 15th percentile?b) What IQ represents the 98th percentile?c) What’s the IQR of the IQs?
In a data set of 1057 New York homes offered for sale, a histogram of the ages looks like this:We drew 1000 samples of 105 homes from this data set and found the IQR and the range of each sample.
A researcher investigating the association between two variables collected some data and was surprised when he calculated the correlation. He had expected to find a fairly strong association, yet the
Students in the Economics class discussed in Exercise 31 also wrote these conclusions. Explain the mistakes they made.a) “There was a very strong correlation of 1.22 between Life Expectancy and
Medical researchers followed 1435 middle-aged men for a period of 5 years, measuring the amount of Baldness present (none = 1, little = 2, some = 3, much = 4, extreme = 5) and presence of Heart
Since 1994, the Best Roller Coaster Poll (www.ushsho.com/bestrollercoasterpoll.htm) has been ranking the world’s best roller coasters. In 2013, Bizarro dropped to 4th after earning the top steel
The Pew Research Center asked 2143 U.S. adults and 1055 college presidents to “rate the job the higher education system is doing in providing value for the money spent by students and their
A professor (of something other than statistics!) distributed the following histogram to show the distribution of grades on his 200-point final exam. Comment on the display. # of
The survey of 299 undergraduate students from Exercise 86 in Chapter 2 (data in Student Survey) asked about respondents’ diet preference (Carnivore, Omnivore, Vegetarian) and political alignment
Here is a mosaic plot of the data on Fish consumption and Prostate cancer from the Step-by-Step Example on page 72.a) From the mosaic plot, about what percent of all men in this survey were diagnosed
Consider the survey data in Exercise 1. a) What is the conditional distribution (in percents) of college presidents’ opinions about the value of college?b) Find the conditional distribution of
Here are the same data as in Exercise 5 but displayed differently:a) Describe what this plot shows using the concept of a conditional distribution.b) Do you think the differences here are real?
In 2015, the website NewGeography.com listed its ranking of the best cities for job growth in the United States. The magazine’s top 20 large cities, along with their weighted job rating indices,
Here is a mosaic plot of the data from Exercise 1 on whether college provides value from a survey of U.S. adults and college presidents:a) From the mosaic plot, about what percent of the respondents
The Centers for Disease Control and Prevention provide data on smoking rates by year and for men and women separately. Here is a table with some of that information:a) What was the smoking rate among
Are the patterns seen in Exercises 5 and 6 relating diet to political opinion the same for men and women? Here are two contingency tables:Data From Exercise 5The survey of 299 undergraduate students
The data set Student survey contains 299 responses to a student survey from a statistics project. The questions asked included:◆ How would you rate yourself politically? (1 = Far left, 9 = Far
In a random sample of U.S. adults surveyed in December 2011, Pew Research asked how important it is “to you personally” to be successful in a high-paying career or profession. Here is a table
The following table summarizes 1529 films from 2014 and 2015 that have been classified into a genre and have a MPAA rating.a) What percent of these films were rated R?b) What percent of these films
Look again at the table of smoking prevalence in exercise 19.a) Compare the smoking rate among 18–24-year-old women to that of men during the time covered by this table.b) Relatively few women over
Pew Research surveyed 5006 U.S. adults to ask their opinions about the state of jobs in the United States in 2016 (www.pewsocialtrends.org/2016/10/06/the-state-ofamerican- jobs/) Respondents were
Pew Research (www .pewsocialtrends.org/2013/03/14/modern-parenthood-roles-ofmoms- and-dads-converge-as-they-balance-work-and-family/) surveyed parents and asked how many hours they spent in various
The New York Times combined survey data (economix.blogs.nytimes.com/2013/ 07/10/working-parents-wanting-fewer-hours/) with data from the U.S. Bureau of Labor Statistics (BLS) (www.bls.gov/news
The Pew Research survey cited in Exercise 27 also asked what employment sector the respondents worked in and whether their job gave them a sense of identity or whether it was “just what they do for
Here is a mosaic plot of the data on being successful from Exercise 10:a) Are the differences in sample sizes in the four groups very large?b) Which factor seems more important in determining how
Here is a mosaic plot of the data on Diet and Politics from Exercise 5 combined with data on Gender.Data From Exercise 5The survey of 299 undergraduate students from Exercise 86 in Chapter 2 (data in
A recent article in Geophysical Research Letters (Asteroid impact effects and their immediate hazards for human populations, 10.1002/2017GL073191) simulated the consequences of an earth impact by an
In Exercise 5 you were asked whether you thought the differences in political identification across diet preferences were real. To examine that question further, we randomly scrambled the students’
The boxplot shows the fuel economy ratings for 67 model year 2012 subcompact cars. Some summary statistics are also provided. The extreme outlier is the Mitsubishi i-MiEV, an electric car whose
In Exercise 8 you were asked to compare the responses of college presidents and all U.S. adults to the question about the value of a college education. To examine that question further, we randomly
Here is a display of the international load factors by month for the period from 2000 to 2016:Discuss the patterns you see in this display. International Load
Here are the same three prices as in Exercise 15 but for 576 cities around the world.a) In general, which commodity is the most expensive?b) Is a carton of eggs ever more expensive than a cappuccino?
Here is a display of the domestic load factors by year through 2015:Discuss the patterns you see in this display. Domestic Load Factor 82.5 75.0 67.5 60.0 T Տրոիզըծո PRRes: T 0 1 2 3 4 5 6 7
Discoveries of planets beyond our solar system have grown rapidly. Here is a histogram showing the distance (in lightyears) from earth to stars that have known planets (as of 2016):Explain why it
The Men’s Giant Slalom skiing event consists of two runs whose times are added together for a final score. Two displays of the giant slalom times in the 2014 Winter Olympics at Sochi are shown
Look at the boxplots by month in Exercise 5. The long low whisker for the year 2001 is due to the terrorist attacks of 9/11. Do you think the data for the months affected by that attack should be set
Here are boxplots of weekly gas prices for regular gas in the United States as reported by the U.S. Energy Information Administration for 2009 through August 2016:a) Compare the distribution of
Because of the skewness of the distributions of fusion times described in Exercise 49, we might consider a re-expression. Here are the boxplots of the log of fusion times. Is it better to analyze the
A National Vital Statistics Report (www.cdc.gov/nchs/) provides information on deaths by age, sex, and race. Below are displays of the distributions of ages at death for White and Black males:a)
The U.S. Department of Energy (www. fueleconomy.gov/feg/download.shtml) provides fuel economy and pollution information on over 1200 2016 car models. Here is a boxplot of Combined Fuel Economy (using
From Exercise 16 it appeared that the mean cost of a cappuccino was slightly higher than the mean cost of a dozen eggs. Given the variation among the prices, could that difference be due just to
From Exercise 50 it appeared that the mean log fusion time for the VV group was greater than that of the NV group. Could the difference be due to chance? The histogram below shows the difference in
In Chapter 2 (Exercise 16) we saw data on shoe sizes of students, reported in European sizes. For the men, the mean size was 44.65 with a standard deviation of 2.03. To convert euro shoe sizes to
The boxplots display the heights (in inches) of 130 members of a choir by the part they sing.a) It appears that the median height for sopranos is missing, but actually the median and the upper
Clarksburg Bakery is trying to predict how many loaves to bake. In the past 100 days, they have sold between 95 and 140 loaves per day. Here is a histogram of the number of loaves they sold for the
In a study of dialysis, researchers found that “of the three patients who were currently on dialysis, 67% had developed blindness and 33% had their toes amputated.” What kind of display might be
Beanstalk Clubs are social clubs for very tall people. To join, a man must be over 6'2"tall, and a woman over 5'10". The National Health Survey suggests that heights of adults may be Normally
A credit card bank is investigating the incidence of fraudulent card use. The bank suspects that the type of product bought may provide clues to the fraud. To examine this situation, the bank looks
One Thursday, researchers gave students enrolled in a section of basic Spanish a set of 50 new vocabulary words to memorize. On Friday, the students took a vocabulary test. When they returned to
As part of the course work, a class at an upstate NY college collects data on streams each year. Students record a number of biological, chemical, and physical variables, including the stream name,
Public relations staff members at State U. phoned 850 local residents. After identifying themselves, the callers asked the survey participants their ages, whether they had attended college, and
The shoe size data for women has a mean of 38.46 and a standard deviation of 1.84. To convert to U.S. sizes, use US size = Euro Size x 0.7865 - 22.5.a) What is the mean women’s shoe size for these
Based on long-term investigation, researchers have suggested that the acidity (pH) of rainfall in the Shenandoah Mountains can be described by the Normal model N(4.9, 0.6).a) Draw and carefully label
One of the authors has an adopted grandson whose birth family members are very short. After examining him at his 2-year checkup, the boy’s pediatrician said that the z-score for his height relative
For the shoe sizes in Exercise 16, what might be the problem with either the standard deviation or the IQR as a measure of spread?Data From Exercise 16A last is a form, traditionally made of wood, in
In 2015 the Council of Europe published a report entitled The European School Survey Project on Alcohol and Other Drugs (www.espad.org). Among other issues, the survey investigated the percentages of
The table gives the numbers of passenger car occupants killed in accidents in 2011 by car type.Convert this table to a relative frequency table. Subcompact and
The frequencies of traffic fatalities of nonoccupants of vehicles are shown in the following bar chart. (www.the-numbers.com/research-analysis) Change this to a bar chart of relative frequencies.
The Motion Picture Association of America (MPAA) rates each film to designate the appropriate audience. The ratings are G, PG, PG-13, and R. The pie chart shows the MPAA ratings of the same 891
The ratings of the 20 top-grossing movies in the years 2006, 2008, 2012, and 2014 are shown in the following bar charts. The pie charts show the same data but are unlabeled. Match each pie chart with
Here are two histograms showing the annual number of traffic fatalities in passenger cars. (NHTSA) One plots the years, and the other plots the fatalities.a) There are gaps in the histogram for Year.
The National Center for Health Statistics (NCHS) conducts an extensive survey consisting of an interview and medical examination with a representative sample of about 5000 people a year. The
Here are the same histograms as in Exercise 7. However, the two groups of fatalities have been highlighted, and the corresponding bars in the Year histogram are also highlighted.a) How many years are
The pie chart summarizes the genres of the 891 MPAA rated movies released in 2014 and 2015.a) Is this an appropriate display for the genres? Why or why not?b) Which category was least common?
Some companies offer 401(k) retirement plans to employees, permitting them to shift part of their before-tax salaries into investments such as mutual funds. Employers typically match 50% of the
The Cleveland Casting Plant is a large, highly automated producer of gray and nodular iron automotive castings for Ford Motor Company. The company is interested in keeping the pouring temperature of
A study of body fat on 250 men collected measurements of 12 body parts as well as the percentage of body fat that the men carried. Here is a dotplot of their bicep circumferences (in inches). What
Load the Kentucky Derby 2016 data into your preferred statistics package and answer the following questions;a) What was the name of the winning horse in 1880?b) When did the length of the race
Load the Indy 500 2016 data into your preferred statistics package and answer the following questions:a) What was the average speed of the winner in 1920?b) How many times did Bill Vukovich win the
The U.S. Census Bureau keeps track of the number of adoptions in each state (and Washington, DC). (www.census .gov) The upper histogram shows the distribution of adoptions.The lower histogram shows
The study in Exercise 9 actually measured the bicep circumference in centimeters. The dot plot in Exercise 9 was formed by dividing each measurement by 2.54 to convert it to inches. Here is the dot
Here are the life expectancies at birth in 190 countries (2014) as collected by the World Health Organization.a) Describe the shape.b) How many modes do you see? Countries 40 30 20 10 48 58 68 Life
Describe the shape of the distribution of bicep circumferences (in inches) for the 250 men in the study of Exercise 10.Data From Exercise 10The study in Exercise 9 actually measured the bicep
For the 146 life expectancies in Exercise 15,a) Which would you expect to be larger: the median or the mean? Explain briefly.b) Which would you report: the mean or the median? Explain briefly.Data
For the distribution of e-mails sent by students in Exercise 11, describe the shape.Data From Exercise 11A university teacher saved every e-mail received from students in a large introductory

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