Hi Shantanu,

I was studying some statistics these days to get more into the WHYs. I studied Chi-Square test and could understand WHAT is to be done. But no book could explain WHY. I could not understand why we do Chi Square test. But from the GB classes I know where should we use it. (though I understand the scope and utility of Chi Square test would be much wider and I know little less than a whisker) Can you please help me with more conceptual parts of Chi-Square test...(and distribution, if you have time)

Rohit

Though this question was not directed to me, let me add a quick response. You use Chi Square test primarily to test dependence or independence. In other words, (using an example) you may wish to know whether the defectives % is same for all shifts. If the test disproves the null, you conclude that defective % are different. In other words -

• defective % DOES depend on shift
  

or

• defective % is not INDEPENDENT of shift.