Chapter 2: Graphical Depictions of Data

distribution

a way to describe the structure of a particular data set or population

frequency distribution

a display of the values that occur in a data set & how often each value/range of values occurs

frequencies

the numbers of data values in the categories of a frequency distribution

relative frequency

the fraction or percentage of the data set that falls into a particular class/category

Formula:

f (frequency) / n (sample size)

grouped frequency distribution

a frequency distribution where the categories or class are ranges of possible values

class width

the difference between the lower and upper limits of two consecutive classes of a frequency distribution

Formula:

([Largest Upper Limit] - [Smallest Lower Limit]) / # of categories

lower class limit

the smallest number that can belong to a particular category/class

upper class limit

the largest number that can belong to a particular category/class

class boundary

the value that lies halfway between the upper limit of one class and the lower limit of the next class

class midpoint

the value that lies halfway between the upper & lower limit of the same class

cumulative frequency

the sum of frequencies of a given class and all previous classes

• the ________ _________ of the very last class = sample size

Pie Charts

Shows how large each category is in relation to the whole

Bar Graphs

uses bars to represent the amount of data in each category

Pareto Charts

bar graphs in which the bars appear in descending order (from largest to smallest)

side-by-side bar graph

used when the bar graph needs to compare the same categories for different groups

stacked bar graph

more efficient for displaying data from different samples

frequency histogram

a special type of type of bar graph of a frequency distribution of quantitative data

relative frequency histogram

histogram where the heights of the bars represent the relative frequencies of each class

frequency polygons

a visual display created by plotting a point at the frequency of each class above each class midpoint & connecting the points using straight lines

Ogive (Oh-jive)

a line graph which depicts the cumulative frequency of each class using the upper class boundaries

Stem-and-leaf plots

a graph for quantitative data similar to a histogram in the way that it visually displays the distribution