Statistics, Graphs and Examples What you need to support your “must knows”
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Transcript of Statistics, Graphs and Examples What you need to support your “must knows”
Statistics, Graphs and Examples
What you need to support your
“must knows”
Measures of Central Tendency
• Mean: Average; sum divided by number of measurements in a data set
• Median: Middle number in a data set
• Mode: Most frequently occurring number in a data set
X-Y Scatterplot
• Graph used to determine the relationship between two variables
• Relationship may be positive, negative or non-existent
• Correlation does not mean causation!!!
Year 2000 - Burlington VTRelationship Between Snowfall and
Temperature
0
10
20
30
40
0 20 40 60 80
Temperature in degrees F
Snow
fall
in in
ches
Bar Graph
• Histogram
• Graph used to show frequencies on the Y axis and characteristics on the X axis
• Used for discrete data
Suspected Nuclear Weapons
1550015000
482 410 200 100 60 200
2000
4000
6000
8000
10000
12000
14000
16000
18000
Source: Center for Defense Information
Line Graph
• Graph used to plot continuous data over time
• X axis contains timeline, Y axis shows frequencies
NYC Handwashing 1992- 1997
0
5
10
15
20
25
30
35
40
1992 1993 1994 1995 1996 1997
Per
cent
age
was
ing
hand
s
Pie Chart
• Graph used to show percentage of a meaningful whole
American Car Colors Year 2000
18%
17%
11%9%9%7%
29%
Silver
White
Black
Green
Blue
Red
Other
Source: Dupont Auto Color Survey
According to the Experts...
• Fonts with serifs are easier to read in print• Fonts sans serif are easier to read when
projected
Read Carefully...
• Random is not the same as a sample
• Be suspicious of research sponsored by a product supplier
• Celebrities often know little about their causes
In general…
• Use data from careful research and sampling polls
• Telling stories is useful to provide a personal touch
• It’s OK to give Personal opinion• Use Internet research from a credible site• Journals are preferable to popular periodicals
And, don’t forget...
• Know your subject
• Know your audience