Chapter 2.

After constructing any relative frequency​ distribution, what should be the sum of the relative​ frequencies?

1 or​ 100%

When describing the distribution of a categorical​ variable, the category that appears most often is called the

mode.

A frequency distribution lists the​ _________ of occurrences of each category of​ data, while a relative frequency distribution lists the​ _________ of occurrences of each category of data.

number proportion

Which two graphs allow the reader to retrieve the original list of​ data?

​Stem-and-leaf plots and dotplots

Explain the difference between a bar graph and a Pareto chart.

A Pareto chart is a particular type of bar graph in which the bars are drawn in decreasing order of height.

Which of the following is not a difference between bar charts and​ histograms?

A bar chart is used for numerical variables while a histogram is used for categorical variables.

Suppose that you have data which indicates that​ 90% of adults in a nearby town have cell phones. Of those who have cell​ phones, 30% use Carrier​ A, 30% use Carrier​ B, 10% use Carrier​ C, 20% use Carrier​ D, 5% use Carrier​ E, and​ 5% use other carriers. Would a bar graph or pie chart be better if the goal is to compare Carrier B and Carrier​ C? Explain.

A bar graph would be better since you are trying to compare two​ parts, not a part to the whole. The angles might be difficult to judge on a pie​ chart, making it hard to directly compare two sectors.

Identify which of these methods can be used to distort a bar graph.

A.making the width of the bars proportional to their height B. stretching the vertical scale C.starting the vertical axis at a point other than the origin

What is an advantage to using a​ stem-and-leaf plot instead of a histogram to display​ data?

A​ stem-and-leaf plot allows for retrieval of the original data from the plot while the histogram does not.

What are Pareto​ charts?

Bar charts that are sorted from most frequent to least frequent

What are two commonly used graphs to display the distribution of a sample of categorical​ data?

Bar graph and pie chart

What is the most common trick to mislead readers of bar​ graphs?

Change the scale of the vertical axis so that it does not start at 0.

Because the human eye has a difficult time judging how much area is taken up by the​ wedge-shaped slice of a pie​ chart, which of the following is true of pie​ charts?

Pie charts are not commonly used by statisticians or in scientific settings.

Which of the following is not a valid point of comparison between histograms and bar​ graphs?

Histograms always have horizontal​ bars, while bar graphs can be either horizontal or vertical.

What is the first step in almost every investigation of​ data?

Make an appropriate graph.

Which information can you obtain from a​ stem-and-leaf plot but not from a​ histogram?

Minimum and maximum data values

When summarizing graphs of categorical​ data, report the _____________ and describe the ________________

Mode(s) variability

Suppose you want to know if more technical service calls are made to homes with cable television or with satellite dish television. Should you use frequencies or relative frequencies to make the​ comparison? Why?

Relative frequencies should be used since there is likely a difference in the number of users of cable and satellite television. If you make comparisons using​ frequencies, the results can be very misleading for different population sizes.

Which of the statements below is true concerning bar​ graphs?

The height of each bar represents the​ category's frequency or relative frequency.

True or​ false? A histogram and a relative frequency​ histogram, constructed from the same​ data, always have the same basic shape.

True. A relative frequency histogram will have a different scale on the​ y-axis but the same shape as a regular histogram.

A categorical variable is only called bimodal under what​ circumstances?

Two categories are nearly tied for most frequent outcomes.

Suppose that you have data which indicates that​ 90% of adults in a nearby town have cell phones. Of those who have cell​ phones, 30% use Carrier​ A, 30% use Carrier​ B, 10% use Carrier​ C, 20% use Carrier​ D, 5% use Carrier​ E, and​ 5% use other carriers. Which of the following is not a reasonable graph to display this​ information?

histogram

​A(n) ____________________ is a bar graph in which the height of each rectangle is the frequency or relative frequency of the class. The width of each rectangle is the​ same, and the rectangles touch each other.

histogram