Chi-Square Test

2015-01-13

azim58 - Chi-Square Test

When should a Chi-Square test be used?

Use the chi (pronounced KY as in sky) square test to look at whether
actual data differ from a random distribution. For example, say you want
to find out whether students prefer particular T-shirt colors. Assume
there are five different colors and each student could get one free at
registration (there are enough so that everyone could choose the same
color). If people chose at random, the proportion of each color chosen
would be equal (about 20% of the total shirts chosen would be in each
category). You might not be surprised to find 19% of the shirts chosen
were red and 21% were black, but when do you have enough evidence to say
people are choosing them non-randomly? This test will tell you.
http://depts.alverno.edu/nsmt/stats.htm

Chi square tests can only be used on actual numbers and not on
percentages, proportions, means, etc.
http://math.hws.edu/javamath/ryan/ChiSquare.html

A non-parametric test, like chi square, is a rough estimate of
confidence; it accepts weaker, less accurate data as input than
parametric tests (like t-tests and analysis of variance, for example) and
therefore has less status in the pantheon of statistical tests.
Nonetheless, its limitations are also its strengths; because chi square
is more 'forgiving' in the data it will accept, it can be used in a wide
variety of research contexts.
http://uk.answers.yahoo.com/question/index?qid=1006032701456

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