Please help me I need to analyze the chisquare test statisti

Please help me, I need to analyze the chi-square test statistic formula. X^2=sum((O-E)^2/E)

THESE ARE QUESTIONS I NEED ANSWERED IN A BASIC LEVEL: Why are we doing a summation? Why is the square of the difference use? Why do we divide by E? And In the end, what does the value of chi-square relate (that is, what does a large value versus a small value imply)?

Solution

The Student\'s t-test and Analysis of Variance are used to analyse measurement data which, in theory, are continuously variable. Between a measurement of, say, 1 mm and 2 mm there is a continuous range from 1.0001 to 1.9999 m m.

But in some types of experiment we wish to record how many individuals fall into a particular category, such as blue eyes or brown eyes, motile or non-motile cells, etc. These counts, or enumeration data, are discontinuous (1, 2, 3 etc.) and must be treated differently from continuous data. Often the appropriate test is chi-squared (c²), which we use to test whether the number of individuals in different categories fit a null hypothesis (an expectation of some sort).

Chi squared analysis is simple, and valuable for all sorts of things - not just Mendelian crosses! On this page we build from the simplest examples to more complex ones. When you have gone through the examples you should consult the checklist of procedures and potential pitfalls.

Then subtract each \"expected\" value from the corresponding \"observed\" value (O-E)

Square the \"O-E\" values, and divide each by the relevant \"expected\" value to give (O-E)²/E

Add all the (O-E)²/E values and call the total \"X²\"