Stat 1350 HW Assignment 1 Unit 1 Lessons 1-2 Essays (1781 words)

Stat 1350 HW Assignment 1 Unit 1 Lessons 1-2 Essays (1781 words) Stat 1350 - Elementary Statistics Graded Homework Assignment 1 Unit 1 - Lessons 1 and 2 1. Athletes' salaries. Here is a small part of a data set that describes Major League Baseball players as of opening day of the 2011 season: (a) What individuals does this data set describe? (b) In addition to the player's name, how many variables does the data set contain? Which of these variables take numerical values? Which of the variables are not numerical variables? (c) What do you think are the units in which each of the numerical variable salary is expressed? For example, what does itmean to give Josh Beckett's annual salary as 17,000? ( Hint: The average annual salary of a Major League Baseball player on opening day, 2011, was $3,305,393.) 2. Sampling moms. Pregnant and breast-feeding women should eat at least 12 ounces of fish and seafood per week to ensure their babies' optimal brain development, according to a coalition of top scientists from private groups and federal agencies. A nutritionist wants to know whether pregnant women are eating at least 12 ounces of fish per week. To do so, she obtains a list of the 340 members of a local chain of prenat al fitness clubs and mails a ques tionnaire to 60 of these women selected at random . Only 21 questionnaires are returned. (a) What is the variable measured in this study? (b) What is the population in this study? (c) What is the sample from which information is actually obtained? (d) What percentage of the women whom the nutritionist tried to contact responded? (e) Is this an observational study or an experiment? 3. Oatmeal and cholesterol. Does eating oatmeal reduce the level of bad cholesterol (LDL)? Here are two ways to study this question. 1. A researcher finds 500 adults over 40 who regularly eat oatmeal or products made from oatmeal. She matches each with a similar adult who does not regularly eat oatmeal or products made from oatmeal. She measures the bad cholesterol (LDL) for each adult and compares both groups. 2. Another researcher finds 1000 adults over 40 who do not regularly eat oatmeal or products made from oatmeal and are willing to participate in a study. She randomly assigns 500 of these to a diet that includes a daily breakfast of oatmeal. The other 500 continue their usual habits. After 6 months, she compares changes in LDL levels. (a) One of these studies is an observational study and the other is an experiment. Identify with study it the experiment and which study is the observational study and explain why for each. (b) Why does the experiment give more useful information about whether oatmeal reduces LDL? 4. Choose your study type. What is the best way to answer each of the questions below: an experiment, a sample survey, or an observational study that is not a sample survey? Explain your choices. (a) Is your school's basketball team called for fewer fouls in home games than in away games? (b) Are college students satisfied with the quality of recreational facilities available to them? (c) Do college students who have access to audio recordings of course lectures perform better in the course than those who don't? 5. Choose your study purpose. Give an example of a question about college students, their behavior, or their opinions that would best be answered by (a) a sample survey. (b) an observational study that is not a sample survey. (c) an experiment. 6. Definitions. What is the difference between a census and a sample survey? 7. Instant opinion. On March 29, 2007, BusinessWeek ran an online poll on their Web site and asked readers the question "Do you think Google is too powerful?" Readers clicked on one of three buttons ("Yes," "No," or "Not sure") to vote. In all, 1336 (35.9%) said "Yes," 2051 (55.1%) said "No," and 335 (9.0%) said "Not sure." (a) What is the sample size for this poll? (b) At the Web site, BusinessWeek includes the following statement about its online poll. "Note: These are surveys, not scientific polls." Explain why the poll may give unreliable information. (c) Just above the poll question was the following statement: "Google's accelerating lead in search and its moves into software and traditional advertising are sparking a