Exam 4: Numerical Descriptive Techniques

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.

The interquartile range is the difference between the:

Longevity and Salary A sample of eight observations of variables x (years of experience) and y (salary in $1,000s) is shown below: -{Longevity and Salary Narrative} a. Calculate the coefficient of correlation, and comment on the relationship between x and y. b. Give a possible reason that the correlation is negative.

The difference between the largest and smallest observations in an ordered data set is called the range.

The advantage that the coefficient of correlation has over the covariance is that the former has a set lower and upper limit.

If a data set is composed of 5 different numbers, there are ____________________ modes.

Which of the following is a measure of variability?

Which measure(s) of central location is/are meaningful when the data are ordinal?

What statistics and graphs can you use to answer the following question: Where is the approximate center of the distribution?

Ages of Jockeys The following data represent the ages in years of a sample of 25 jockeys from a local race track: 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. -{Ages of Jockeys Narrative} Compute the interquartile range of the data and interpret its meaning.

Salaries of Office Workers The following data represent the salaries (in thousands of dollars) of a sample of 13 office workers 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. -{Salaries of Office Workers Narrative} Compute the variance and standard deviation of the salaries, and express the numbers in the appropriate units.

Which of the following is a property of r, the coefficient of correlation?

In a negatively skewed distribution, the mean is smaller than the median and the median is smaller than the mode.

The variance is more meaningful and easier to interpret compared to the standard deviation.

The line drawn within the box of a box plot always represents the mean.

Which of the following statements is true for the following observations: 9, 8, 7, 9, 6, 11, and 13?

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. -{Weights of Police Officers Narrative} What does the histogram tell you about the distribution of the weights of workers?

While Chebysheff's Theorem applies to any distribution, regardless of shape, the Empirical Rule applies only to distributions that are bell shaped.

If cov(x, y) = 20, and then the sample coefficient of correlation r is:

The interquartile range is found by taking the difference between the 1st and 3rd quartiles and dividing that value by 2.