Exam 3: Numerical Descriptive Techniques

The coefficient of correlation r is a number that indicates the direction and the strength of the linear relationship between the dependent variable y and the independent variable x.

Weights of Police Officers: The following data represent the weights in pounds of a sample of 25 police officers: 164, 148, 137, 157, 173, 156, 177, 172, 169, 165, 145, 168, 163, 162, 174, 152, 156, 168, 154, 151, 174, 146, 134, 140, and 171. -Construct a relative frequency histogram for the data, using five class intervals and the value 130 as the lower limit of the first class.

Longevity and Salary: A sample of eight observations of variables x (years of experience) and y (salary in $1,000s) is shown below: -Draw the scatter diagram and plot the least squares line.

In a histogram, the proportion of the total area which must be to the right of the mean is:

In symmetric data, the value for Q₂ is always halfway between Q₁ and Q₃.

Ages of Retirees: A sociologist recently conducted a survey of retirees over 65 years of age whose net worth is too high to qualify for Medicaid and who have no private health insurance. The ages of 20 uninsured retirees were as follows: 65, 66, 67, 68, 69, 70, 71, 73, 74, 75, 78, 79, 80, 81, 86, 87, 91, 92, 94, and 97. -Identify the interquartile range of the ages of the uninsured retirees. What does this value tell you about the data?

Ages of Retirees: A sociologist recently conducted a survey of retirees over 65 years of age whose net worth is too high to qualify for Medicaid and who have no private health insurance. The ages of 20 uninsured retirees were as follows: 65, 66, 67, 68, 69, 70, 71, 73, 74, 75, 78, 79, 80, 81, 86, 87, 91, 92, 94, and 97. -Calculate the third quartile of the ages of the uninsured retirees.

Yearly Donations: The following data represent the yearly donations (in thousands of dollars) of a sample of 13 benefactors: 26.5, 23.5, 29.7, 24.8, 21.1, 24.3, 20.4, 22.7, 27.2, 23.7, 24.1, 24.8, and 28.2. -Compute median.

The ____________________ is the least effective of all the measures of variability.

If two data sets have the same range, the distances from the smallest to largest observations in both sets will be the same.

The number of hours a college student spent studying during the final exam week was recorded as follows: 7,6, 4, 9, 8, 5, and 10. Compute for the data and the value in an appropriate unit.

The median of a set of data is more representative than the mean when the mean is larger than most of the observations.

Assuming a linear relationship between X and Y, if the coefficient of correlation (r) equals -0.75, this means that:

$\mu$ is a population parameter and is a sample statistic.

Which of the following statements about the mean is not always correct?

Hours of Playing Video Games: Suppose that the following data provide the hours of playing video games per week for a sample of 15 high school students in Roanoke, Virginia: 5, 11, 25, 19, 18, 20, 27, 13, 8, 10, 15, 19, 18, 9, and 12. -Calculate and interpret the interquartile range.

According to the Empirical Rule, if the data form a bell shaped normal distribution approximately ____________________ percent of the observations will be contained within 1 standard deviation around the mean.

In a histogram, the proportion of the total area which must be to the left of the median is less than 0.50 if the distribution is negatively skewed.

The ____________________ mean of n returns (or growth rates) is the appropriate mean to calculate if you wish to estimate the mean rate of return (or growth rate) for any single period in the future.

The strength of the linear relationship between two interval variables can be measured by the: