Exam 1: Describing Data With Graphs

Describe the difference between a population and a sample, and provide two examples for each.

The class interval in a frequency distribution is the number of data values falling within each class.

Absenteeism A high school band teacher has a record of each student's absence. The results, in days, are 3, 4, 7, 2, 2, 1, 0, 0, 1, 0, 3, 3, 2, 1, 6, 0, 1, 0, 1, 1, 1, 5, 3, 1, 1, 0, 0, 2, 1, 2, 1, 0, 0, and 4. -Refer to the Absenteeism statement. What proportion of students has been absent at least two days?

Suppose you are given a stem-and-leaf plot that describes two-digit integers between 30 and 80. For one of the classes displayed, the row appears as 5|234. In this case, the numerical values being described are 25, 35, and 45.

Bivariate data result when fewer than two variables are measured on a single experimental unit.

How many classes should generally be used when constructing a relative frequency histogram?

Which of the following terms refers to the set of all possible observations about a specified characteristic of interest?

A skewed histogram is one with a long tail extending either to the right or left.

A variable is a characteristic that changes over time, and/or varies for different individuals or objects under consideration. An experimental unit is the individual or object on which a variable is measured.

In the term "frequency distribution," frequency refers to the number of data values or measurements falling within each class.

Friendly Encounter The Executive Board of a popular online dating website, called Friendly Encounter, wanted to know how to market the site by targeting the age groups most likely to be interested in its product. To find out, a random sample of 250 users was drawn from its database of participants who had been active during the previous month. The users were then categorized into age groups. The average frequency of access per week was recorded for each age group. The result was organized into the following table of data: -Refer to the Friendly Encounter table. Just from the statistics alone, should the Board decide to target the under-40 age group, rather than the 40 & over group? Explain your conclusion.

Garbage Weight A garbage carrier would like to start charging by the weight of a customer's garbage rather than the number of cans. The weights (in kilograms) of 90 randomly selected cans of garbage are summarized in the chart below. -Refer to the Garbage Weight table. Construct the frequency histogram.

In general, how do data distributions of incomes of employees in large firms tend to be shaped?

A histogram is a graphical device. What kind of data is it commonly used to display?

Social Media The Executive Board of a popular social media website wanted to know which kinds of professional people were accessing their website regularly over a two-month period. To that end, a random sample from its database of active users was collected. The following data were recorded: -Refer to the Social Media table. From the data gleaned, approximately what proportion of their users are academics?

A branch of the statistics discipline that is used to develop and utilize techniques for properly making inferences about population characteristics based on information contained in a sample drawn from this population is called inferential statistics.

Which of the following might best be displayed using a bar chart?

Garbage Weight A garbage carrier would like to start charging by the weight of a customer's garbage rather than the number of cans. The weights (in kilograms) of 90 randomly selected cans of garbage are summarized in the chart below. -Refer to the Garbage Weight table. What percentage of the cans weigh at least 24.9 kilograms?

A relative frequency histogram can be constructed by letting either the horizontal axis or the vertical axis represent the variable of interest.

A histogram is said to be symmetric if, when we draw a vertical line down the centre of the histogram, the two sides are identical in shape and size.