BIOL2608 Biometrics Computer lab session II

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Nov 30, 2013 (3 years and 11 months ago)

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BIOL2608 Biometrics

Computer lab session II

Testing for goodness of fit



Chi square test

Chi square goodness of fit


Infers whether a population conforms to a
specified theoretical distribution from a
sample of nominal scale data



Chi square goodness of fit


H
0
: the sample data came from a population
following a specified theoretical distribution



H
A
: the sample data came from a population
NOT following a specified theoretical distribution




,
e
i

= expected value,
o
i

= observed value


k = number of categories

Example


In a survey, 100 students were asked whether
they have experience travelling to Europe.


39 have travelled to Europe and 61 have not.



H
0
: The results were obtained by chance
(expected frequencies: 50 travelled and 50 not travelled)


H
A
: The results were not obtained by chance

Example


Probability that H
0

is accepted.

Can be checked from Chi table
with calculated Chi Square.

Related Readings


Zar, J. H. (1999).
Biostatistical Analysis,
4th edition. New Jersey:
Prentice
-
Hall.


Chapter 22.1

Your demonstrators

Adela Li

lijingecology@gmail.com

Kevin Ho

kyho2@hku.hk


Andy Yi

yixianliang120@hotmail.com

Edward Lau

tclau36@hku.hk

Vera Chan

verabschan@gmail.com