# STA 1020 Lecture 4: 2.2

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Wayne State University

Statistics Course

STA 1020

Carolyn Hochstadt

Fall

Description

2.2
Main graphs that you have to know about:
Bar Graph
Pie Chart
Stem and leaf plot
Histogram
Line Graph/time series graph
Graphs should be able to stand alone without original data
Graphs must have the following:
Title
Labeled axes
Legend, source, date when appropriate
Pie Chart: shows how large each category is in relation to the whole; qualitative data
-Multiply 360 by relative frequency to get size of each wedge
*just eyeball it
Example:
Percentages- F/n
20/49=41% or 15/49=31%
*Your percentages should total 100%
Bar Graph: graphs that use bars to represent the amount of data in each category; qualitative data
The order of the bars does not matter
Bars on a bar graph DO NOT touch
You can also use percentages instead of the numbers
Frequency Histogram: a bar graph of frequency distribution of quantitative data
Relative Frequency Histogram: a histogram in which the heights of the bars represent the relative
frequencies of each class rather than simply the frequencies. A histogram looks like a bar graph
Frequency distribution is how many times a piece of quantitative data appears
Horizontal axis is a real number line
The width of the bars represents class width; they should be uniform
The bars SHOULD touch
The height of the bars represents frequency
Stem and Leaf Plot: a graph of quantitative data that is similar to a histogram in the way that it visually
displays the distribution; quick way to depict the frequencies of the data without having to first create
frequency distribution
It is more detailed than a histogram
It is not good to use if you are trying to display a large number of data
Ex: all of the heights of Wayne State students
Should have the following:
Leaves- last digit; can only be a single digit
Stem- remaining digits
Key
The leaves must be in numerical order!!!!!!
You have to write down every number in between
Leave the leaf blank if you don’t have that number! Do not put a zero!
Example:

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