Answer:
meta-analysis
Explanation:
Meta-analysis involves the statistical procedure of combining data and results from multiple studies and trying to determine or draw relevant conclusions from here.
From the example above, Dr. DiLorenzo combines results from a number of studies of same topic to investigate the relationship between two variables. He is doing a meta-analysis.
Demographic Transition
Population aging is a by-product of the process known as "<em>Demographic Transitioning</em>." This process is determined mostly by fertility and mortality rate. For example: a population that has a high fertility rate has a low amount of older people, and vise versa.