A knowledge of basic statistics is important for the researcher.

Chi-Square:  A common analysis needed by the researcher is the comparison of two groups of data where the results can be categorized into only a few types of results.  For example: Comparing the results of two different techniques of closing a tympanic membrane perforation.  The results can be categorized into two types:  Perforation closed or perforation not closed.  

A Chi-Square test can be used to analyze this type of comparison:

• For more about Chi-Square and a two-by-two online calculator go to
  http://math.hws.edu/javamath/ryan/ChiSquare.html 

• Two-by-two calculator with Fisher's Exact Test and Yates' Correction
  http://www.graphpad.com/quickcalcs/contingency1.cfm  

• For an online Chi-Square Calculator which uses up to nine rows and columns go to:  http://www.physics.csbsju.edu/stats/contingency_
  NROW_NCOLUMN_form.html 

• Download a two-by-two calculator
  http://escuela.med.puc.cl/recursos/recepidem/CHIsquare.xls 

• Other Online Chi-Square Calculators:
  http://people.ku.edu/~preacher/chisq/chisq.htm