Maintaining a conversational, humorous, and informal writing style, this new edition engages students from the first page. Instant download and all chapters are included. MyStatLab not included. YOU are the protagonist of your own life. For one-or-two semester introductory statistics courses. Finally, 2. Generally, the handguns that are involved in buyback programs are not the same caliber as handguns used in homicides in Milwaukee.
Movies by genre and rating. The last picture show. So patrons under 13 can see only This supports the assertion that approximately three-quarters of movies can only be seen by patrons 13 years old or older. There are White graduates and total graduates. Of those, , or about Of those, 27, or about Of those, 21, or about More about seniors. Caution should be used with the percentages for Minority graduates, because the total is so small. Still, the conditional distributions of plans are essentially the same for the two groups.
There is little evidence of an association between race and plans for after graduation. Politics revisited. Female Male d Politics and sex do not appear to be independent in this course.
Although the percentage of liberals was roughly the same for each sex, females had a greater percentage of moderates and a lower percentage of conservatives than males. Magnet schools revisited.
More politics. The percentage of self-identified Liberals and Moderates who are female is about twice the percentage of Conservatives who are female. This suggests that sex and politics are not independent.
Back to school. There were 1, qualified applicants for admission to the magnet schools program. Overall, Asians accounted for Parking lots. Here is the same table, with row and column totals. Foreign cars are defined as non-American.
The conditional distribution of Origin for Staff is: Driver Although students appear to own a higher percentage of European cars and a smaller percentage of American cars than the staff, the two groups own nearly the same percentage of Asian cars.
However, because of the differences, there is evidence of an association between Driver and Origin of the car. So, the forecast was correct a total of times. On days when it did not rain, forecasters were correct in their predictions out of times These two percentages are very close.
There is no evidence of an association between the type of weather and the ability of the forecasters to make an accurate prediction. Twin births. Twin Births in thousands a Of the , Preterm Preterm mothers who Induced or Level of without Term or had twins in Caesarean Prenatal Care procedures Postterm Intensive 18 15 28 , Adequate 46 43 65 63, had Inadequate 12 13 38 inadequate Total 76 71 health care during their pregnancies.
This is evidence of an association between level of prenatal care and twin birth outcome. If these variables were independent, we would expect the percentages to be roughly the same. Generally, those mothers who received adequate medical care were more likely to have preterm births than mothers who received intensive medical care, who were in turn more likely to have preterm births than mothers who received inadequate health care. This does not imply that mothers should receive inadequate health care do decrease their chances of having a preterm birth, since it is likely that women that have some complication during their pregnancy that might lead to a preterm birth , would seek intensive or adequate prenatal care.
Blood pressure. Generally, an association between two variables does not imply a cause-andeffect relationship. Specifically, these data come from only one company and cannot be applied to all people. Furthermore, there may be some other variable that is linked to both age and blood pressure. Only a controlled experiment can isolate the relationship between age and blood pressure. Obesity and exercise. Within each classification of BMI column , participants self reported exercise levels.
Therefore, these are column percentages. While it may seem logical that lack of exercise causes obesity, association between variables does not imply a cause-and-effect relationship. Only a controlled experiment could isolate the relationship between BMI and level of physically activity.
These data provide no evidence that Prozac might be helpful in treating anorexia. Even though the percentage was higher for the placebo patients, this does not mean that Prozac is hurting patients. Antidepressants and bone fractures.
These data provide evidence that taking a certain class of antidepressants SSRI might be associated with a greater risk of bone fractures. At younger ages, males form the slight majority of drivers. The percentage of male drivers continues to shrink until, at around age 45, female drivers hold a slight majority. This continues into the 85 and over category. Younger drivers are slightly more likely to be male, and older drivers are slightly more likely to be female.
If having a tattoo and having hepatitis C were independent, we would have expected these percentages to be roughly the same. Discharge delayed Large Small Total Hospital Hospital of 10 of 50 of 10 of 20 of 30 of of 30 of of Major surgery patients were delayed of times, or about Minor Surgery patients were delayed 30 of times, or about 6. The small hospital has the lower overall rate of delayed discharge. Even though small hospital had the lower overall rate of delayed discharge, the large hospital had a lower rate of delayed discharge for each type of surgery.
While the overall rate of delayed discharge is lower for the small hospital, the large hospital did better with both major surgery and minor surgery. Minor surgery had a lower delay rate than major surgery 6.
Simply put, it is a mistake to look at the overall percentages. The real truth is found by looking at the rates after the information is broken down by type of surgery, since the delay rates for each type of surgery are so different. The larger hospital is the better hospital when comparing discharge delay rates. Delivery service. Boxes R Us is better at delivering Regular and Overnight packages.
Boxes R Us delivers a greater percentage of its packages Overnight, where it is comparatively harder to deliver on time. Pack Rats delivers many Regular packages, where it is easier to make an on-time delivery.
Graduate admissions. Total of of b of Females are accepted at a higher rate in every program. The overall percentage is an unfair average. It fails to take the different numbers of applicants and different acceptance rates of each program.
Women tended to apply to the programs in which gaining acceptance was difficult for everyone. Be a Simpson! The three-way table below shows one possibility. The number of local hires out of new hires is shown in each cell.
The given boxplot could be displaying a distribution that has multiple modes the first histogram , is reasonably unimodal the second histogram , has gaps and clusters the third histogram , or has outliers the fourth histogram.
The histogram indicates a skewed distribution when the bars on one side of the histogram are generally taller than the bars on the other side of the histogram.
The boxplot does not show this. These cannot be determined from the histogram. Section 3. Using the Outlier Rule 1. Since the maximum, minutes, is above the upper fence, there is at least one high outlier.
Lower Fence:. Since the mean age at adoption is higher than the median age at adoption, the distribution of adoption ages is likely to be skewed to the right, with many adoptions happening when children are relatively young, with fewer adoptions of older children. Adoptions II. The mean number of adoptions is expected to by higher than the median number of adoptions, since the distribution of the number of adoptions is skewed to the right.
Test score centers. The median test score will not be affected, but the mean test score will increase by 0. Test score spreads. The IQR of the test scores will not be affected, but the standard deviation of the test scores will increase. If the outlier is removed, the standard deviation will decrease. The IQR will not change substantially. It may change slightly, since removing one value from the data set may change the quartiles, which would change the IQR.
Chapter Exercises 9. Not a histogram. In the news. In the news II. Thinking about shape. Most students will have very few speeding tickets maybe 0 or 1 , but a small percentage of students will likely have comparatively many 3 or more? Open Golf Tournament would most likely be unimodal and slightly skewed to the right. The best golf players in the game will likely have around the same average score, but some golfers might be off their game and score 15 strokes above the mean.
Remember that high scores are undesirable in the game of golf! Most newborns have about the same weight, with some babies weighing more and less than this average. There may be slight skew to the left, since there seems to be a greater likelihood of premature birth and low birth weight than post-term birth and high birth weight.
The average hair length of the males would be at one mode, and the average hair length of the females would be at the other mode, since women typically have longer hair than men. The distribution would be skewed to the right, since it is not possible to have hair length less than zero, but it is possible to have a variety of lengths of longer hair.
More shapes. The average age of the players would be at one mode and the average age of the spectators probably mostly parents would be at the other mode. The distribution would be skewed to the right, since it is possible to have a greater variety of ages among the older people, while there is a natural left endpoint to the distribution at zero years of age.
Most people would have 0, 1, or 2 siblings, with some people having more siblings. Sugar in cereals. The lower cluster shows a bit of skew to the right. Adult cereals often advertise low sugar content. No chorus member has height below 60 inches or above 76 inches. Most vineyards are smaller than 90 acres, with a few larger ones, from 90 to acres. One vineyard was larger than all the rest, over acres. The mode of the distribution is between 0 and 30 acres.
Run times. The distribution of runtimes is skewed to the right. The shortest runtime was around A typical run time was between 30 and 31 minutes, and the majority of runtimes were between 29 and 32 minutes. It is easier to run slightly slower than usual and end up with a longer runtime than it is to run slightly faster than usual and end up with a shorter runtime. This could account for the skew to the right seen in the distribution.
Heart attack stays. The distribution is centered around 8 days, with the majority of the hospital stays lasting between 1 and 15 days.
There are a relatively few hospital stays longer than 27 days. Many patients have a stay of only one day, possibly because the patient died. The distribution is centered at about 2 emails, with many students only sending 1 email. There is one outlier in the distribution, a student who sent 21 emails. The next highest number of emails sent was only 8.
Super Bowl points The third quartile is Super Bowl wins The third quartile is 19 points. The second highest winning margin was only 36 points. Tornadoes The first quartile is 40 deaths and the third quartile is The IQR will likely be unaffected, since the new maximum has no effect on the quartiles.
Sick days. The company probably uses the mean, while the union uses the median number of sick days. The mean will likely be higher, since it is affected by probable right skew. Some employees may have many sick days, while most have relatively few. Standard deviation I. Both sets have the same mean 6 but set two has values that are generally farther away from the mean. Both sets have the same mean 15 , maximum 20 , and minimum 10 , but 11 and 19 are farther from the mean than 14 and Although the measures of center and position change, the spread is exactly the same.
Standard deviation II. Both sets have the same mean 7 , maximum 10 , and minimum 4 , but 6 and 8 are farther from the mean than 7. Although the measures of center and position are different, the spread is exactly the same. Since the Range of Set 2 is greater than the Range of Set 1, the standard deviation is also larger.
Pizza prices. The mean and standard deviation would be used to summarize the distribution of pizza prices, since the distribution is unimodal and symmetric. Neck size. The mean and standard deviation would be used to summarize the distribution of neck sizes, since the distribution is unimodal and symmetric. Pizza prices again. Neck sizes again. There are a few points as far away as 3 inches from the mean, and none as far away as 5 inches.
Those are too large to be the standard deviation. Movie lengths This is near the center of the unimodal and slightly skewed histogram, with the outlier set aside. Only 3 movies ran that long. While the distribution of movie lengths is generally skewed to the right, which would raise the mean, there is a low outlier, which would lower the mean. The actual mean of Golf drives Movie lengths II The interquartile range is 18 minutes.
The interquartile range is better, since it is resistant to outliers. Golf drives II And time was flying. Perhaps if we make him a new house and a bigger bed, and promise him plenty of monkey-servants to work for him and to make life pleasant for him--perhaps then he will not wish to go. Chee-Chee, the great Traveler, is about to speak!
He owes money in Puddleby; and he says he must go back and pay it. He serves as a Statistics consultant to the College Board, leading numerous institutes and workshops for AP Statistics teachers. Paul F. Velleman has a global reputation for innovative Statistics education. He got an A. His research often deals with statistical graphics and data analysis methods. Richard D. Stats: Data and Models promotes conceptual understanding for applied statistics without overwhelming the reader with tedious calculations and complex mathematics.
De Veaux, Richard D. Velleman, Cornell University, David E. Bock, Cornell University, Augustin M.
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