Exam 4: Numerical Descriptive Techniques

In a positively skewed distribution, which of the following is the correct statement?

The standard deviation is expressed in terms of the original units of measurement but the variance is not.

The interquartile range is a measure of variability in a set of data.

Weights of Teachers The following data represent the weights in pounds of a sample of 25 teachers: 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. -{Weights of Teachers Narrative} Which is a better measure of variability in the weights of the teachers, the standard deviation or the coefficient of variation?

The units for the standard deviation are the same as the units for the original data (for example, feet, inches, etc.).

Test Scores Suppose that an analysis of a set of test scores reveals that: Q₁ = 45, Q₂ = 85, Q₃ = 105. -{Test Scores Narrative} What do these statistics tell you about the shape of the distribution of test scores?

Which of the following statistics is a measure of central location?

____________________ techniques give you the big picture of a distribution and ____________________ techniques give you more precise details.

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. -{Hours of Playing Video Games Narrative} Calculate and interpret the interquartile range.

The mean of a sample of 15 measurements is 35.6 feet.Suppose that the sample is enlarged to 16 measurements, by including one additional measurement having a value of 42 feet.Find the mean of the sample of the 16 measurements.

Which of the following summary measures is affected most by extreme values?

The ____________________ measures the spread between the middle 50% of the observations.

A sample of 13 college professors has a mean age of 30 years and a standard deviation of 5 years.Suppose that the sample is enlarged to 15 college professors, by including two additional professors that are each 30 years old.Will the standard deviation increase, decrease, or stay the same, and why?

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. -{Yearly Donations Narrative} Compute median.