Chapter 2

Frequency Table

A tabular summary of a data showing the frequency of items in each of the distinct categories

Symmetric Distribution

a distribution in which it is a mirror image of itself on both sides of its center

Negatively Skewed Distribution

a distribution that has a skew to the left because it has a long tail extending off to the left and reflects a small number of relatively small observations

Positively Skewed Distribution

a distribution that has a tail that extends to the right and reflects the presence of a small number of relatively large observations

Bar Graph

a graphical display of data where each category is depicted by a unique bar with the height of the bar representing the frequency, or proportion, of observations in that category

Pie Chart

a graphical display of data where each category is depicted by a unique slice of the pie, in degrees, which represents the frequency, or proportion, of observations in that category

Histogram

a series of rectangles where the width and height of each rectangle represent the interval width and frequency (or relative frequency) of the respective interval

Scatterplot

a set of (X,Y) points, where X and Y each represent one of the numerical variables, and each point on the coordinate plane represents the (X,Y) coordinates for each observation; helps determine whether or not two numeric variables are related in some systematic way

A/B Testing

a way to compare two versions of something to see which one is better as measured by some performance indicator

Polygon

connects a series of neighboring points where each point represents the midpoint of a particular class and its associated frequency or relative frequency

Ogive

connects a series of neighboring points where each point represents the upper limit of a particular interval and its associated cumulative frequency or cumulative relative frequency

Line Chart

connects the consecutive observations of a numerical variable with a line; tends to be used to track changes of the variable over time

Stacked Column Chart

designed to visualize more than one categorical variable, plus it allows for the comparison of composition within each category; depicts a contingency table

Frequency Distribution

divides the data into non-overlapping intervals and records the number of observations that fall into each interval

Stem-and-Leaf

gives an overall picture of where the observations are centered and how they are dispersed from the center

Cumulative Frequency Distribution

records the number of observations that falls below the upper limit of a particular interval

Cumulative Relative Frequency Distribution

records the proportion (or fraction) of observations that falls below the upper limit of a particular interval

Relative Frequency Distribution

records the proportion (or fraction) of observations that falls into each interval

Contingency Table

shows the frequencies for two categorical variables, x and y, where each cell represents a mutually exclusive combination of the pair of x and y values

Scatterplot with a categorical variable

the incorporation of categorical variables into a basic scatterplot; common to encode the categorical variable through point color