1 1 pts In a simple linear regression problem, the correlation coefficient r and the slope b1: -must be equal to each other. -must have the same sign. -must have opposite signs. -are not related. Question 2 1 pts Which of the following assumptions in a simple linear regression problem is stated incorrectly? The distribution of the error term is normal. The mean of the error term is 0. The variance of the error term increases as x increases. The errors are independent. Question 3 1 pts The _________ measures the strength and direction of the linear relationship between the dependent and the independent variable. Coefficient of correlation Intercept Predicted value None of the above. Question 4 1 pts Linear regression can achieve which of the following? Identify how much variable y will change if variable x changes. Predict someone's Biostatistics grade from her mathematical ability. If the weather gets 30% colder, then the sales of scarves will increase by 50%. All of the above. Question 5 1 pts A biostatistician finds the relationship between the number of weeks (x) spent in a hospital and number of seizures per week (y) and is described by the following equation: . This is based on a sample size of 50 patients and the associated coefficient of correlation is, r = -.93. Using this information answer the following question: How many seizures per week would you predict for a person who has been at the hospital for ten weeks? 24.0 5.8 14.9 -.91 Question 6 1 pts A biostatistician finds the relationship between the number of weeks (X) spent in a hospital and number of seizures per week (Y) and is described by the following equation: . This is based on a sample size of 50 patients and the associated coefficient of correlation is , r = -.93. Using this information above, answer the following question: How do you interpret r = -.93? There is a perfect positive relationship between the number of weeks spent in a hospital and the number of seizures recorded. There is a perfect negative relationship between the number of weeks spent in a hospital and the number of seizures recorded. There is a strong negative relationship between the number of weeks spent in a hospital and the number of seizures recorded. There is a strong positive relationship between the number of weeks spent in a hospital and the number of seizures recorded. Question 7 1 pts The range of the correlation coefficient is? -1 to 0. 0 to 1 -1 to 1 None of the above Question 8 1 pts Researchers are interested to know if cell phone use is associated with lower sperm motility. De Luliis et al. (2010) conducted an experiment in which they exposed normal human sperm dishes to cell phone electromagnetic signals and measured the production of intracellular reactive oxygen species (ROS) produced in cellular mitochondria that can damage DNA as well as the amount of DNA damage. The following table shows the data for this study. Sperm with Mitochondria ROS (%) x 8 29 6 13 16 27 18 30 25 25 23 15 11 Sperm with DNA Damage (%) y 5 18 3 8 10 15 5 13 15 7 8 4 3 Based on the above data, the estimated linear regression is Question 9 1 pts Based on the above data, what is the estimated correlation coefficient? .65 -.81 .50 .81 Question 10 1 pts Two variables have a positive association when the values of one variable tend to increase as the values of the other variable increase. the values of one variable tend to decrease as the values of the other variable increase. the values of one variable tend to increase regardless of how the values of the other variable change. the values of both variables are always positive