Exam 2: Describing the Distribution of a Single Variable

Seventy percent of the job applicants scored above what value?

A sample of a population taken at one particular point in time is categorized as:

Because they represent such extreme values, outliers should be eliminated from statistical analyses.

Suppose that a sample of 10 observations has a standard deviation of 3. Then the sum of the squared deviations from the sample mean is 30.

Phone numbers, Social Security numbers, and zip codes are typically treated as numerical variables.

A histogram that is positively skewed is also called:

Is the distribution of the number of children symmetrical or skewed? How do you know?

Compute the mean number of children.

Which statement is true for the following data values: 7, 5, 6, 4, 7, 8, and 12?

Cross-sectional data are data on a population at a distinct point in time, whereas time series data are data collected over time.

Categorizing age variables as "young," "middle-aged," and "elderly" is an example of:

Are the empirical rules applicable in this case? If so, apply them and interpret your results. If not, explain why the empirical rules are not applicable here.

Unlike histograms, box plots depict only one aspect of a variable.

A sample of 20 observations has a standard deviation of 4. The sum of the squared deviations from the sample mean is:

What is the most common type of chart for showing the distribution of a numerical variable?

Researchers are conducting a review of the "war against poverty" in the latter half of the twentieth century. As part of their analysis, the proportion of Americans under the age of 18 who lived below the poverty line for each of the years 1959 through 2000 is used to generate the following time series plot. ​ How successful was the United States in its efforts to win "the war against poverty" for the nation's children during this time period?

Statistics professor has just given a final examination in his statistical inference course. He is particularly interested in learning how his class of 40 students performed on this exam. The scores are shown below. -What are the mean and median scores on this exam?

The value of the mean times the number of observations equals the sum of all of the data values.

The core purpose of time series graphs is to detect historical patterns in the data.

A population includes all elements or objects of interest in a study, whereas a sample is a subset of the population used to gain insights into the characteristics of the population.