Statistics Chapter 3 Quiz and Test
The correlation coefficient measures
the strength of the linear relationship between two quantitative variables
The correlation between the heights of fathers and the heights of their fully grown sons if r=.52. This value was based on both variables being measured in inches. If fathers' heights were measured in feet, and sons' heights were measured in furlongs, the correlation between heights of fathers and headlights of sons would be
unchanged: equal to .52
In a statistics course, a linear regression equation was computed to predict the final exam score from the score on the first test. The equation was y= 10+.9x where y is the final exam score and x is the score on the first test. Carla scored 95 on the first test. Bill scored a 90 on the first test and a 93 on the final exam. What is the value of his residual?
2.0
In a statistics course, a linear regression equation was computed to predict the final exam score from the score on the first test. The equation was y= 10+.9x where y is the final exam score and x is the score on the first test. Carla scored 95 on the first test. What is the predicted value of her score on the final exam?
95.5
Which of the statements below about least squares regression are correct? I. Switching the explanatory and response variables will not change the least-squares regression line. II. The slope of the line is very sensitive to outliers in the x direction with large residuals. III. A value of r^2 close to 1 does not guarantee that the relationship between the variables is linear.
Both II and III are correct
A study is conducted to determine if one can predict the academic performance of a first year college student based on their high school grade point average. The explanatory variable in this study is
Grade point average in high school
One concern about the depletion of the ozone layer is the increase in UV light will decrease crop yields. Which of the following is correct?
If the UV values increases by one Dobson unit, the yield is expected to decrease by .0463
(Temperature and Car stopping Scatterplot) Do these data provide strong evidence that warmer temperatures cause a greater stopping distance?
No. we can't be sure the temperature is responsible for the difference in stopping distances.
A set of data describes the relationship between the size of annual salary raises and the performance ratings for employees of a certain company. The least squares regression equation is y=1400+2000x where y is the raise amount and x is the performance rating. Which of the following statements must be true?
The actual relationship between salary raises and performance rating is linear.
All but one of the following statements contains an error. Which statement could be correct?
The correlation between mid-august soil moisture and the per-acre yield of tomatoes is r=.53
(residual plot for weights of basketball players) What does the residual plot tell you about the linear model?
The curved pattern in the residual plot suggests that the linear model is not appropriate.
Other things being equal, larger automobile engines are less fuel-efficient. You are planning an experiment to study the effect of engine size on the fuel efficiency of sport utility vehicles. In this study,
a gas mileage is a response variable, and you expect to find a negative association
If two variables are positively associated, then
larger values of one variable are associated with larger values of the other.
One concern about the depletion of the ozone layer is the increase in UV light will decrease crop yields. The least-squares regression line is the line that
minimizes the sum of squared residuals between the actual yield and the predicted yield.
(Temperature and Car stopping Scatterplot) If the stopping distance was expressed in yards instead of feet, how would the correlation r between temperature and stopping distance change?
r would not change
