Test of association between two variables is done by-
X2
Correlation
Regression
None
Ref:Parks 23rd edition pg 852 In order to find out whether there is significant association or not between the two variables , coefficient or Corelation is calculated . r lies between -1 and +1 r near -1 : indicates strong negative correlation . r = 0 : indicates no association r near +1: indicates strong positive correlation. Note: correlation does not necessarily prove causation . Chi-square test offers an alternate method of testing the significance of difference between two propoions.Advantage: it can also be used when more than 2groups are to be compared.
Biostatistics