Category: Uncategorized

The correlation coefficient between the hours that a person is awake during a 24-hour period and the hours that same person is asleep during a 24-hour period is most likely to be 

A regression analysis of students’ college grade point averages (GPAs) and their high school GPAs found R2 = 0.311. Which of these is true?I. High school GPA accounts for 31.1% of college GPA.II. 31.1% of college GPAs can be correctly predicted with this model.III. 31.1% of the variance in college GPA can be accounted for by the model 

A researcher wants to compare the performance of three types of pain relievers in volunteers suffering from arthritis. Because people of different ages may suffer arthritis of varying degrees of severity, the subjects are split into two groups: under 60 and over 60. Subjects in each group are randomly assigned to take one of the medications. Twenty minutes later they rate their levels of pain. This experiment … 

Of A-D, which is not a critical part of designing a good experiment?

The model  can be used to predict the stopping distance (in feet) for a car traveling at a specific speed (in mph). According to this model, about how much distance will a car going 65 mph need to stop? 

In an experiment the primary purpose of blinding is to reduce …

A correlation of zero between two quantitative variables means that 

The correlation coefficient between high school grade point average (GPA) and college GPA is 0.560. For a student with a high school GPA that is 2.5 standard deviations above the mean, we would expect that student to have a college GPA that is the mean. 

Researchers who wanted to see if drinking grape juice could help people lower their blood pressure got 120 non-smokers to volunteer for a study. They measured each person’s blood pressure and then randomly divided the subjects into two groups. One group drank a glass of grape juice every day while the other did not. After sixty days the researchers measured everyone’s blood pressure again. They reported that differences in changes in blood pressure between the groups were not statistically significant.a. Was this an experiment or an observational study? Explain briefly.b. Briefly explain what “not statistically significant” means in this context.c. Briefly explain why the researchers randomly assigned the subjects to the groups.d. Since everyone’s blood pressure was measured at the beginning and at the end of the study, the researchers could have simply looked at the grape juice drinkers to see if their blood pressure changed. Briefly explain why the researchers bothered to include the control group.e. Briefly explain why the researchers studied only non-smokers.f. Other researchers now plan to replicate this study using both smokers and non-smokers. Briefly describe the design strategy you think they should use. 

A polling organization is investigating public opinion about cloning. They phone a random sample of 1200 adults, asking each person one of these questions (randomly chosen):A: “Do you favor allowing doctors to use cloned cells in attempts to find cures for such terrible diseases as Alzheimer’s, diabetes, and Parkinson’s?”B: “Should research scientists be allowed to use cloned human embryos in their experiments?”Which question do you expect will elicit greater support for cloning? Explain. What kind of bias is this?