Principios de
Estad́ıstica
Graphical
Tools
Principios de Estad́ıstica
Leonardo Collado Torres y Maŕıa Gutiérrez Arcelus
Licenciatura en Ciencias Genómicas, UNAM
www.lcg.unam.mx/~lcollado/index.php
www.lcg.unam.mx/~mgutierr/index.php
Cuernavaca, México
Febrero - Junio, 2009
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Principios de
Estad́ıstica
Graphical
Tools
Exploratory Data Analysis with R
1 Graphical Tools
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Principios de
Estad́ıstica
Graphical
Tools
Diaps. de Jim
Estas diapositivas corresponden a las 28, 29 y 30 de la
presentación EDA de Jim.
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Principios de
Estad́ıstica
Graphical
Tools
boxplots
boxplot : A plotting method for generating Tukey’s
boxplots.
Excellent for comparing location shifts of k distributions of
varying size.
Assess skewness and spread of either of one or more
distributions.
Boxplots are often a much better summary of a
distribution than are histograms as they do not suffer from
either bandwidth choice or the need to have large data
sets.
Example
What does skewness look like on a boxplot, spread? can we
generate some data to exemplify these things? (hint:
remember all of the random number generators which we
talked about in the first lecture)
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Principios de
Estad́ıstica
Graphical
Tools
Anatomy of a boxplot
A, B : lower/upper adjacent values:
r ,
|q75 − q25|
(1)
A =
inf{xi : xi > q25 − 1.5r}
(2)
B =
sup{xi : xi < q75 + 1.5r}
(3)
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Principios de
Estad́ıstica
Graphical
Tools
Anatomy of a boxplot
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−2−10123The anatomy of a Boxplot
outlier
outlier
outlier
A
B
q0.25
q0.5
q0.75
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