I am new to the Chi-Square idea so excuse me if this is a stupid question. But when I go online, it says that the Chi-Square statistic is:c2=Ei(OiEi) where O is the observed and E is the expected value. However, when I go to my notes, it says thatV=21i=1n(XiX)2c2 from the Cochran's Theorem with Xi being random variables. I don't understand what V is and what the chi-square is and its relation to the normal distribution. This whole thing is just confusing.