Study Ch 2 - BattalyClass Notes 2.5 MISLEADING GRAPHS Study Ch 2.5 GOALS: Recognize graphs that are...
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Distribution Shapes; Misleading Graphs G. Battaly © G. Battaly 2018 1 January 24, 2018 Class Notes: Prof. G. Battaly, Westchester Community College, NY Statistics Home Page Class Notes 2.4 DISTRIBUTION SHAPES The shape of the distribution of a data set determines the statistical methods. Study Ch 2.4 GOALS: 1. Use the organized data (graphs) to evaluate the distribution of the data. 2. Compare distribution to known shapes. Class Notes: Prof. G. Battaly, Westchester Community College, NY Statistics Home Page Class Notes 2.4 DISTRIBUTION SHAPES What is the Shape of the Distribution? Need descriptions of general shapes for comparison.
Transcript of Study Ch 2 - BattalyClass Notes 2.5 MISLEADING GRAPHS Study Ch 2.5 GOALS: Recognize graphs that are...
Distribution Shapes; Misleading Graphs G. Battaly
© G. Battaly 2018 1
January 24, 2018
Class Notes: Prof. G. Battaly, Westchester Community College, NYStatistics Home Page Class Notes
2.4 DISTRIBUTION SHAPES
The shape of the distribution of a data set determines the statistical methods.
Study Ch 2.4
GOALS:1. Use the organized data (graphs) to evaluate the distribution of the data.2. Compare distribution to known shapes.
Class Notes: Prof. G. Battaly, Westchester Community College, NYStatistics Home Page Class Notes
2.4 DISTRIBUTION SHAPES
What is the Shape of the Distribution?
Need descriptions of general shapes for comparison.
Distribution Shapes; Misleading Graphs G. Battaly
© G. Battaly 2018 2
January 24, 2018
Class Notes: Prof. G. Battaly, Westchester Community College, NYStatistics Home Page Class Notes
2.4 DISTRIBUTION SHAPESWhat is the Shape of the Distribution?
bell triangular uniform
Jshape reverse J
Right skewed Left skewed
bi modal multi modal
Characteristics of Shapes
1. Modality: number of peaks uni modal 1 peak bi 2 multi >3
2. Symmetry: close to a mirror image about center 3. Skewed: tails off to right or left, not symmetrical
Class Notes: Prof. G. Battaly, Westchester Community College, NYStatistics Home Page Class Notes
2.4 DISTRIBUTION SHAPES
Distribution Shapes; Misleading Graphs G. Battaly
© G. Battaly 2018 3
January 24, 2018
How does the Shape of a Sample compare to that of the Population?
Class Notes: Prof. G. Battaly, Westchester Community College, NYStatistics Home Page Class Notes
Consider the number of BW hawks that were counted at the Hook Mountain Hawk Watch in the years 2004 to 2013 to be the population under consideration. This graph shows the distribution of those hawks across the season from Sep 1 to Oct 5, using the average of the 10 counts for each specific day.
2.4 DISTRIBUTION SHAPES
Class Notes: Prof. G. Battaly, Westchester Community College, NYStatistics Home Page Class Notes
population
samples
Big BW Day:Sep 17, 2011
2.4 DISTRIBUTION SHAPES
Distribution Shapes; Misleading Graphs G. Battaly
© G. Battaly 2018 4
January 24, 2018
Class Notes: Prof. G. Battaly, Westchester Community College, NYStatistics Home Page Class Notes
population
samples
Distribution of Samples from the Population are similar to but not equal to that of the Population
Big BW Day:Sep 17, 2011
2.4 DISTRIBUTION SHAPES
What shape does this distribution have?
Class Notes: Prof. G. Battaly, Westchester Community College, NYStatistics Home Page Class Notes
2.4 DISTRIBUTION SHAPES
Distribution Shapes; Misleading Graphs G. Battaly
© G. Battaly 2018 5
January 24, 2018
Class Notes: Prof. G. Battaly, Westchester Community College, NYStatistics Home Page Class Notes
2.4 DISTRIBUTION SHAPES
What shape does this distribution have?
Class Notes: Prof. G. Battaly, Westchester Community College, NYStatistics Home Page Class Notes
2.4 DISTRIBUTION SHAPES
Distribution Shapes; Misleading Graphs G. Battaly
© G. Battaly 2018 6
January 24, 2018
What shape does this distribution have?
Class Notes: Prof. G. Battaly, Westchester Community College, NYStatistics Home Page Class Notes
2.4 DISTRIBUTION SHAPES
What shape does this distribution have?
Class Notes: Prof. G. Battaly, Westchester Community College, NYStatistics Home Page Class Notes
2.4 DISTRIBUTION SHAPES
Distribution Shapes; Misleading Graphs G. Battaly
© G. Battaly 2018 7
January 24, 2018
What shape does this distribution have?
Class Notes: Prof. G. Battaly, Westchester Community College, NYStatistics Home Page Class Notes
triangle, approximately symmetrical
2.4 DISTRIBUTION SHAPES
What shape does this distribution have?Class Notes: Prof. G. Battaly, Westchester Community College, NY
Statistics Home Page Class Notes
2.4 DISTRIBUTION SHAPES
Some shape are difficult to categorize. May need more data.
Distribution Shapes; Misleading Graphs G. Battaly
© G. Battaly 2018 8
January 24, 2018
Class Notes: Prof. G. Battaly, Westchester Community College, NYStatistics Home Page Class Notes
2.5 MISLEADING GRAPHS
Study Ch 2.5
GOALS: Recognize graphs that are misleading
1. Truncated graphs suggest larger changes than actually occur.2. Inaccurate plotting of data.3. Improper scaling can imply larger changes.
Class Notes: Prof. G. Battaly, Westchester Community College, NYStatistics Home Page Class Notes
2.5 MISLEADING GRAPHS1. Truncated Graphs: truncates vertical axis > differences appear larger than actual
sometimes justified to clarify differences then use // on vertical axis (only have 1 day, want to see phenomenon of thousands)
Distribution Shapes; Misleading Graphs G. Battaly
© G. Battaly 2018 9
January 24, 2018
Class Notes: Prof. G. Battaly, Westchester Community College, NYStatistics Home Page Class Notes
2.5 MISLEADING GRAPHS1. Truncated Graphs: truncates vertical axis > differences appear larger than actual
sometimes justified to clarify differences then use // on vertical axis
Class Notes: Prof. G. Battaly, Westchester Community College, NYStatistics Home Page Class Notes
2.5 MISLEADING GRAPHS
1. Truncated Graphs: truncates vertical axis > differences appear larger than actual
sometimes justified to clarify differences then use // on vertical axis
Distribution Shapes; Misleading Graphs G. Battaly
© G. Battaly 2018 10
January 24, 2018
Class Notes: Prof. G. Battaly, Westchester Community College, NYStatistics Home Page Class Notes
2.5 MISLEADING GRAPHSMisleading graphs
Source: Fox News would you accept this graph as correct?
Note: Unemployment 5.0 Percent in December 2015, Bureau of Labor Statistics
Class Notes: Prof. G. Battaly, Westchester Community College, NYStatistics Home Page Class Notes
2.5 MISLEADING GRAPHSMisleading graphs
truncated
not graphed correctly
Distribution Shapes; Misleading Graphs G. Battaly
© G. Battaly 2018 11
January 24, 2018
Class Notes: Prof. G. Battaly, Westchester Community College, NYStatistics Home Page Class Notes
2.5 MISLEADING GRAPHSMisleading graphs
not graphed correctly
truncated
8%
1%
Class Notes: Prof. G. Battaly, Westchester Community College, NYStatistics Home Page Class Notes
2. Improper scaling: using 2D graphs to represent values, so need to use area properly
2.5 MISLEADING GRAPHS
AWhich best represents twice the amount of A?
