Chi Squared test Flashcards
When are contingency tables used?
They are used when two have two variables that can take different values and you want to find the extent to which they are related.
What is chi squared statistic measuring? What is its formula.
It measures how far the observed frequencies are from the expected.Its formula is chi squared=sum of (fo-fe)^2/fe
What are the degrees of freedom for a contingency table?
(n-1)x(m-1).
What type of test is chi squared usually and when do we accept h0 for a test of association?
It is right tailed, we accept h0 when the test statistic value is less than = the critical value.
When is Yate’s correction used and what is the formula for it?
It is used in 2x2 tables.The formula is chi sqaured =sum of (|oi-ei-0.5)^2/ei
What type of distribution is the chi squared one and what is its parameter?
It is a continuous random distribution and its parameter is v degrees of freedom.
When might we need to merge cells or colums?
When expect frequency is below 5.
When conducting chi squared contingency tables hypothesis tests, what is our h0?
That the two variables are independent.
How to find degrees of freedom in goodness of fit tests?
V=number of classes-number of estimated parametrs-number of restrictions.
