STATS 200 Sophia Introduction to Statistics Milestone 1_ (2020) – University of Maryland

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STATS 200 Sophia Introduction to Statistics Milestone 1_ (2020) – University of Maryland Cindy measured and recorded the temperature of a liquid for an experiment. She used a poorly calibrated th... ermometer and noted the temperature as 100.5 degrees Fahrenheit. The actual temperature of the liquid was 95 degrees Fahrenheit. The percent error in her calculation is __________. • 5.79% • 4.08% • -5.79% • -4.08% RATIONALE Recall that the percent error is equivalent to the absolute difference divided by the actual value. If the absolute measure is 95 degrees and the observed measure is 100.5 degrees, then the absolute error is: So we calculate the percentage error to be: CONCEPT Absolute Change and Relative Change 2 A trainer is studying the effects of vitamin D on his athletes. He has realized that there are many potential confounding factors, such as gender and age. To limit the effect of these confounding variables, he decided to first group two athletes together based on these variables (for example, two 21-year-old males). Then he randomly assigned one person to receive the vitamin D and the other to receive a sugar pill. What type of experimental design does this situation demonstrate? • Randomized Block Design • Simple Random Design • Completely Randomized Design • Matched-Pair Design RATIONALE By matching on age and gender this is called a matched-pair design. CONCEPT Matched-Pair Design 3 Which of these statements best defines a stratified random sample? • It is a sample where every nth element of the population is selected in a sequence. • It is a sample in which every element has the same chance of being selected from the total population. • It is a sample where the population is divided into roughly equal groups, and then elements are randomly selected from each group. • It is a sample where the population is first broken into groups and then elements are randomly selected, in proportion, from each group. RATIONALE Recall that a stratified random sample is first broken up into homogenous groups called strata. From those strata a random sample is then chosen. CONCEPT Stratified Random and Cluster Sampling 4 Mike wants to find out the approximate income for professors in Michigan. He decides to randomly select 50 professors who work for a college or university in Michigan and obtain their salaries. What are the sample and the population of Mike's study? • The 50 professors that Mike interviews are his sample, and all of the professors who work in Michigan are the population. • The 50 professors that Mike interviews are his sample, and the professors that Mike does not interview are the population. • The professors in Michigan are the sample, and all the professors in the United States are the population. • All of the professors who work in Michigan are the sample, and the 50 professors that Mike interviews are the population. RATIONALE Recall the entire set of interest is the population and a sample is a subset of that population. In this question the entire set are all the professors at a university or college in Michigan, with the sample being the 50 that were chosen to be analyzed about their salary. CONCEPT Sampling 5 Jenae's study ignored the fact that only some of her coffee choices had caffeine, even though her co-workers preferred caffeinated coffee. Therefore, Jenae decided to label one type of decaffeinated coffee as having caffeine to see what would happen. As she anticipated, this coffee became more popular with her co-workers, and they claimed that the extra boost of caffeine helped them focus on their work. The growing popularity of the decaffeinated coffee among co-workers, under the false impression that it gave them extra caffeine, is an example of ________. • a case-control study • a treatment group • a control group • the placebo effect RATIONALE Since no treatment of caffeine was given to these participants in the control group and they reported an effect, this is what we refer to as the placebo effect. CONCEPT Placebo 6 A factory manufactures bolts. One of its employees, working in the quality control department, checks the first 20 bolts manufactured in a day for possible defects. .......continued.......... [Show More]

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