Question 1

The relative frequency is the frequency of a class divided by the total number of measurements.

Accepted Answer

This is the definition of relative frequency.

Question 2

A scatter plot can be used to identify outliers.

Accepted Answer

A scatter plot is used to identify the relationship between two variables.

Question 3

A stem-and-leaf display is a graphical portrayal of a data set that shows the overall pattern of variation in the data set.

Accepted Answer

A stem-and-leaf display does indeed show the overall pattern of variation in a data set through a graphical portrayal.

Question 4

When data are qualitative,the bars should never be separated by gaps.

Accepted Answer

Bar graphs for qualitative data are displayed with a gap between each category.

Question 5

When we wish to summarize the proportion (or fraction)of items in a class,we use the frequency distribution for each class.

Accepted Answer

The relative frequency summarizes the proportion (or fraction) of items in a class. Frequency distribution shows actual counts of items in each class.

Question 6

Stem-and-leaf displays and dot plots are useful for detecting outliers.

Accepted Answer

Stem-and-leaf displays and dot plots allow for easy visualization of a data set and can help identify any values that are unusually far from the rest of the data, indicating the presence of outliers.

Question 7

Beginning the vertical scale of a graph at a value different from zero can cause increases to look more dramatic.

Accepted Answer

This is known as the "y-axis scale distortion" and it can be misleading as it makes small differences appear larger than they actually are. It is important to be aware of this when interpreting graphs with a non-zero starting point on the y-axis.

Question 8

When looking at the shape of the distribution using a stem-and-leaf,a distribution is skewed to the right when the left tail is shorter than the right tail.

Accepted Answer

The answer of When looking at the shape of the...

Question 9

Each stem of a stem-and-leaf display should be a single digit.

Accepted Answer

Leaves on the stem-and-leaf are a single digit.

Question 10

In the first step of setting up a Pareto chart,a frequency table should be constructed of the defects (or categories)in decreasing order of frequency.

Accepted Answer

This is the correct first step in setting up a Pareto chart. The defects or categories should be listed in decreasing order of frequency in a frequency table before creating the chart.

Question 11

A runs plot is a form of scatter plot.

Accepted Answer

A runs plot is a type of scatter plot that displays the relationship between two variables by plotting them as points on a graph with one variable on the horizontal axis and the other variable on the vertical axis.

Question 12

A bar chart is a graphic that can be used to depict qualitative data.

Accepted Answer

A bar chart is a graphic that depicts a frequency, relative frequency, or percent frequency distribution.

Question 13

It is possible to create different interpretations of the same graphical display by simply using different captions.

Accepted Answer

Captions can influence the viewer's perception and understanding of the data presented in a graphical display. Different captions can highlight different aspects of the same data and lead to different interpretations.

Question 14

Splitting the stems refers to assigning the same stem to two or more rows of the stem-and-leaf display.

Accepted Answer

Splitting the stems is a technique used to shorten the length of the display by assigning the same stem to two or more rows when the values become too large to be accommodated in a single column. This is often done when there are gaps in the data or when the values have a limited number of digits.

Question 15

The stem-and-leaf display is advantageous because it allows us to actually see the measurements in the data set.

Accepted Answer

The stem-and-leaf display is a useful tool for organizing and displaying numerical data. It allows us to see individual measurements and the distribution of the data.

Question 16

When constructing any graphical display that utilizes categorical data,classes that have frequencies of 5 percent or less are usually combined together into a single category.

Accepted Answer

This is a common practice in data visualization to improve readability and avoid cluttering the display with too many categories. It is recommended to combine categories with low frequencies into a single category to simplify the display without losing important information.

Question 17

In a Pareto chart,the bar for the OTHER category should be placed to the far left of the chart.

Accepted Answer

The bar for the OTHER category should be placed to the far right of the chart, as it represents the least significant category. The bars should be arranged in descending order of frequency or importance, with the largest category on the left and the smallest category on the right.

Question 18

When establishing the classes for a frequency table,it is generally agreed that the more classes you use,the better your frequency table will be.

Accepted Answer

While having more classes can provide a more detailed breakdown, there is a point where having too many classes can obscure patterns and trends in the data. The number of classes should be chosen carefully to provide a balance between detail and clarity.

Question 19

The sample cumulative distribution function is nondecreasing.

Accepted Answer

The cumulative distribution function (CDF) is defined as the probability that a random variable takes on a value less than or equal to a given number. Therefore, as the value of the number increases, the probability can either stay the same or increase. Hence, the CDF must be nondecreasing.

Question 20

A frequency table includes row and column percentages.

Accepted Answer

A frequency table can include either row percentages or column percentages, but not both.

Quiz 2: Descriptive Statistics: Tabular and Graphical Methods