Dependent variable is the outcome of interest in a regression analysis. It is the variable whose differences (variability) among individuals we would like to explain or predict by using certain factors.
Obesity is a common health problem. One of the several measures of obesity is waist circumference. For the purpose of formulating prevention strategy, one may be interested in exploring factors associated with obesity. In that case, waist circumference should be taken as the dependent variable in a regression analysis. The risk factors are taken as independent variables.
It is sometimes said that the brain size may have indication on intelligence. Brain size may be measured by horizontal resonance images (MRI) while intelligence may be indicated by the Intelligent Quotient (IQ) scores.
As we are interested in determining if brain size can explain the difference of intelligence among different people, IQ will be our dependent variable in the regression analysis.