Individuals with higher incomes have better access to clean water, medical care, and good nutrition, and healthier individuals are likely to be more productive than sick ones.
Correlation refers to the relationship or association that exists between two variables taken into account for the research. There are three types of correlation such as positive, negative and no relation. Positive correlation refers to the situation when one variable is changed the other one will also be changed at the similar rate.
In the given scenario, it is said that there exists a positive correlation between the income per person and the population health. This means that when the individuals receives higher income then they can afford for getting clean water, medical care and also good nutrition and hence the healthier individuals will be more productive than the sick ones. This is because they can go for work without any leave or absence.