Exam 3: Numerical Descriptive Techniques

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. -What does the value of the third quartile tell you?

The ____________________ mean is used whenever we wish to find the "average" growth rate, or rate of change, in a variable over time.

The ____________________ is calculated by finding the middle of the data set, when the data are ordered from smallest to largest.

The variance is a measure of the linear relationship between two variables

If the covariance of x and y is 26.16, and the standard deviation of x is 32.7, then the slope of the least squares line is b₁ =.80.

Salaries of Employees: The following data represent the yearly salaries (in thousands of dollars) of a sample of 13 employees of a firm: 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 the median salary.

Ages of Senior Citizens: A sociologist recently conducted a survey of citizens 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 22 uninsured senior citizens were as follows: 65, 66, 67, 68, 69, 70, 71, 73, 74, 75, 76, 77, 78, 79, 80, 81, 86, 87, 91, 92, 94, and 97. -Explain why there is no mode for this data set.

Compute the variance, and standard deviation of the salaries, and express the numbers in the appropriate units.

The ____________________ of the correlation indicates the direction of a linear relationship.

A box plot is a graphical representation of the 5-number summary.

Is it possible for the standard deviation of a data set to be larger than its variance? Explain.

Is a standard deviation of 10 a large number indicating great variability, or is it small number indicating little variability? To answer this question correctly, one should look carefully at the value of the:

Hours Worked per Week: The following data represent the hours worked per week of a sample of 25 employees from a government department: 31, 43, 56, 23, 49, 42, 33, 61, 44, 28, 48, 38, 44, 35, 40, 64, 52, 42, 47, 39, 53, 27, 36, 35, and 20. -Construct a stem and leaf display for the hours.

Computers: The following data represent the number of computers owned by a sample of 10 families from Chicago: 4, 2, 1, 1, 5, 3, 0, 1, 0, and 2. -Compute the mean number of computers.

Which of the following statements is true?

In a positively skewed distribution:

The value of the standard deviation may be either positive or negative, while the value of the variance will always be positive.

The size of a sample is denoted by the letter ____________________, and the size of a population is denoted by the letter ____________________.

The 5-number summary consists of the smallest observation, the first quartile, the median, the third quartile, and the largest observation.

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