The following are links to sites explaining the Chi square Test. These are basic explanations. There are many videos available on YouTube, but I found these the simplest:
http://www.youtube.com/watch?v=VskmMgXmkMQ
http://www.youtube.com/watch?v=WXPBoFDqNVk
http://biostatistics.cmu.edu.tw/downloads/TCLarea/The%20Chi-Square%20Test.pdf
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