Basic Statistics > A-Level Question Paper > Sophia Stat Milestones, Updated Test_Combined. (All)

Sophia Stat Milestones, Updated Test_Combined.

Document Content and Description Below

Several scientific and statistical studies have been done to determine whether or not pollutants in soil increase the incidence of cancer. A study based on many previous studies summarizes that there ... is no link between pollutants in soil and cancer. This kind of statistical study is called a __________. Clinical trial Prospective study Matched-pair design Retrospective study RATIONALE Since the data has already been collected it is called a retrospective study design. CONCEPT Prospective and Retrospective Studies 2 The blood bank at a hospital has 1,200 units of blood, out of which 37% units are of blood group B+. A clinical researcher randomly selects 300 units of blood and finds that 33% of those are of blood group B+. To test his result, he randomly selects 200 units of blood and finds that 40% of those are of blood group B+. Which of the following is the reason there is a difference between the two percentages selected by the researcher? Random error; the numbers were different due to variability inherent in sampling. Both samples suffered from non-response bias. The samples were not random samples. The sample sizes were both too small. RATIONALE Sophia :: Welcome 7/8/20, 4)11 PM https://snhu.sophia.org/spcc/introduction-to-statistics-2/milestone_take_feedbacks/4608176 Page 2 of 15 When sampling, there is always some variability that occurs. So, although the sample values are different, since they were randomly chosen, the differences are simply due to the variability that comes from sampling and not due to some systematic bias. CONCEPT Random and Systematic Errors 3 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? Simple Random Design Matched-Pair Design Randomized Block Design Completely Randomized Design RATIONALE By matching on age and gender this is called a matched-pair design. CONCEPT Matched-Pair Design 4 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 control group a treatment group a case-control study 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. [Show More]

Last updated: 2 years ago

Preview 1 out of 129 pages

Buy Now

Instant download

We Accept: