Question

State the requirements to perform a goodness of Fit test. Choose the correct answer below:

A. at least 80% of expected frequencies > 5
B. all expected frequencies > 5
C. at least 90% of expected frequencies > 5
D. at least 90% of expected frequencies >10 a
E. t least 80% of expected frequencies > 10
F. all expected frequencies > 1

Answer 1

B. all expected frequencies > 5

Explanation:

The expected number np(i) in any of the classes or cells should not be less than 5. So when the expected number np(i) in any class is less than 5 , we may combine this class with one or more other classes to meet this requirement.

It is clear that chi square will be small when all ni are close to their expected values npi. The chi square will become larger when the difference becomes larger. The chi square thus measures the amount of deviation ( or agreement ) between the observed and expected results.

Thus it is a good approximation if all the expected values npi are sufficiently large and hence chi square distribution confirms with the ( k-1) degrees of freedom.