Slide 1

Part II Sigma Freud & Descriptive Statistics Chapter 4     A Picture is Really Worth a Thousand Words

Why Illustrate Data?  When describing a set of scores you will want

to use two things…

 One score for describing the group of data  Measure of Central Tendency  Measure of how diverse or different the scores

are from one another  Measure of Variability

 However, a visual representation of these two

measures is much more effective when examining distributions.

Ten Ways to a Great Figure  Minimize the “junk”  Plan before you start creating  Say what you mean…mean what you say  Label everything

 Communicate ONE idea  Keep things balanced  Maintain the scale in the graph  Remember…simple is best

 Limit the number of words  The chart alone should convey what you

want to say

Frequency Distributions  Method of tallying, and representing the

number of times a certain score occurs

 Group scores into interval classes/ranges

 Creating class intervals  Range of 2, 5, 10, or 20 is usually good  10-20 class intervals for the entire range of data  Divide total # of data points by # of class

intervals desired to determine numeric range of the class intervals

Histograms  Hand Drawn

Histogram

Histogram  Tally-Ho

Method

Frequency Polygon  A “continuous line that represents the

frequencies of scores within a class interval”

Cumulative Frequency Distribution

Fat & Skinny of Frequency Distributions  Distributions can be different in four different

ways…

 Average value  Variability  Skewness  Kurtosis

Average Value

Variability

Skewness  Positive & Negative Skewness

Kurtosis  Platykurtic (A) & Leptokurtic (C)

Cool Ways to Chart Data  Column Chart

Cool Ways to Chart Data  Line Chart

Cool Ways to Chart Data  Pie Chart

Using the Computer to Illustrate Data  Creating Histogram Graphs

Using the Computer to Illustrate Data  Creating Bar Graphs

Using the Computer to Illustrate Data  Creating Line Graphs

Using the Computer to Illustrate Data  Creating Pie Graphs