Chapter 1: Introduction to Statistics

Discrete/ Continuous Data Which of the following describe discrete data?

a. The numbers of people surveyed in each of the next several years for the National Health and Nutrition Examination Surveys.

b. The exact foot lengths (measured in cm) of a random sample of statistics students.

c. The exact times that randomly selected drivers spend texting while driving during the past 7 days.

In Exercises 21–24, refer to the data in the table below. The entries are white blood cell counts (1000 cells,ML) and red blood cell counts (million cells,ML) from male subjects examined as part of a large health study conducted by the National Center for Health Statistics. The data are matched, so that the first subject has a white blood cell count of 8.7 and a red blood cell count of 4.91, and so on.

Subject

Conclusion: If we analyze the sample data and conclude that there is a correlation between white blood cell counts and red blood cell counts, does it follow that higher white blood cell counts are the cause of higher red blood cell counts?

In Exercises 21–24, refer to the data in the table below. The entries are white blood cell counts (1000 cells,ML) and red blood cell counts (million cells,ML) from male subjects examined as part of a large health study conducted by the National Center for Health Statistics. The data are matched, so that the first subject has a white blood cell count of 8.7 and a red blood cell count of 4.91, and so on.

Conclusion: If we analyze the sample data and conclude that there is a correlation between white blood cell counts and red blood cell counts, does it follow that higher white blood cell counts are the cause of higher red blood cell counts?

Normality Requirement What does it mean when we say that the confidence interval methodsof this section are robust against departures from normality?

Health SurveyIn a survey of 1020 adults in the United States, 44% said that they wash their hands after riding public transportation (based on data from KRC Research).

a. Identify the sample and population.

b. Is the value of 44% a statistic or parameter?

c. What is the level of measurement of the value of 44%? (nominal, ordinal, interval, ratio)

d. Are the numbers of subjects in such surveys discrete or continuous?

What’s Wrong? In Exercises 25–28, identify what is wrong.

Potatoes In a poll sponsored by the Idaho Potato Commission, 1000 adults were asked to select their favorite vegetables, and the favorite choice was potatoes, which were selected by 26% of the respondents.

What’s Wrong? In Exercises 25–28, identify what is wrong.

Potatoes In a poll sponsored by the Idaho Potato Commission, 1000 adults were asked to select their favorite vegetables, and the favorite choice was potatoes, which were selected by 26% of the respondents.

Identify whether the given value is a statistic or a parameter.

In a study of American Airlines flights from JFK in New York to LAX in Los Angeles, 48 flights are randomly selected and the average (mean) arrival time is 8.9 minutes late.

What’s Wrong? In Exercises 25–28, identify what is wrong.

Healthy Water In a USA Today online poll, 951 Internet users chose to respond, and 57% of them said that they prefer drinking bottled water instead of tap water.

Doughnuts and Fat. A classic study, conducted in 1935 by B. Lowe at the Iowa Agriculture Experiment Station, analyzed differences in the amount of fat absorbed by doughnuts in cooking with four different fats. For the experiment, 24 batches of doughnuts were randomly divided into four groups of 6 batches each. The four groups were then randomly assigned to the four fats. What type of statistical design was used for this study? Explain your answer.