Exam 1: Introduction to Statistics

A quality control specialist compares the output from a machine with a new lubricant to the output of machines with the old lubricant.

Explain why using self-reported data instead of measured data is a potential pitfall in data collection. Be sure to include an example.

Which of the following does not apply to the ratio level of measurement?

Use the data in the table to answer the question. The x-values are amounts of saturated fat (in grams) in various regular two-ounce muffins. The y-values are amounts of saturated fat (in grams) in various "low fat" two-ounce muffins. Amounts of Saturated Fat in Regular and Low-Fat Muffins 4.5 3.5 3.7 5.2 4.9 3.9 1.2 2.1 2.2 1.8 1.6 2.2 Note that the table lists measured amounts of saturated fat in two different types of muffin. Given these data, what issue can be addressed by conducting a statistical analysis of the values?

A study shows that adults who work at their desk all day weigh more than those who do not. Conclusion: Desk jobs cause people to gain weight.

A political pollster reports that his candidate has a 10% lead in the polls with 10% undecided.

There are many potential pitfalls that can cause problems when analyzing data. Which of these choices are not classified as a potential pitfall?

Determine whether the given description corresponds to an experiment or an observational study. A stock analyst selects a stock from a group of twenty for investment by choosing the stock with the greatest earnings Per share reported for the last quarter.

"38% of adults in the United States regularly visit a doctor". This conclusion was reached by a college student after she had questioned 520 randomly selected members of her college. What is wrong with her conclusion?

Identify which of these types of sampling is used: random, stratified, systematic, cluster, convenience. -To avoid working late, a quality control analyst simply inspects the first 100 items produced in a day.

The number of stories in a Manhattan building is 22.

The table shows the weights, in pounds, of seven subjects before and after following a particular diet for two months. Assume that the x-values are the weights before the diet and the y-values are the weights after the diet. Subject Before 183 170 150 171 198 160 164 After 176 161 148 176 184 162 152 Are the x-values matched with the corresponding y-values? That is, is each x-value associated with the corresponding y-value in some meaningful way? If the x- and y-values are matched, does it make sense to use the difference between each x-value and the y-value that is in the same column? Why or why not?

Identify the sample and population. Also, determine whether the sample is likely to be representative of the population. An employee at the local ice cream parlor asks three customers if they like chocolate ice cream.

On a test, if 80 questions are answered and 59 of them are correct, what is the percent of correct answers? Round to the nearest percent.

Which type of experiment separates subjects into groups that are similar but differ in ways that might affect the outcome of the experiment?

Provide an appropriate response. -An education expert is researching teaching methods and wishes to interview teachers from a particular school district. She randomly selects ten schools from the district and interviews all of the teachers at the selected Schools. Does this sampling plan result in a random sample? Simple random sample? Explain.

A marketing firm does a survey to find out how many people use a product. Of the one hundred people contacted, fifteen said they use the product. Identify the type of study used.

Identify which type of sampling is used. A tax auditor selects every 1000th income tax return that is received.

Identify the type of observational study (cross-sectional, retrospective, prospective). -A teacher at a school obtains a sample of students by selecting a random sample of 20 students from each grade. What kind of sampling is being used here? Will the resulting sample be a simple random sample of the population of students at the school? Explain your thinking.

Identify the type of observational study (cross-sectional, retrospective, prospective). -A researcher wants to obtain a sample of 100 school teachers from the 800 school teachers in a school district. Describe procedures for obtaining a sample of each type: random, systematic, convenience, stratified, cluster.