relative

[IMPSX-UE]

Epidemiology is the field of medicine that deals with epidemics -outbreaks of disease that affect large numbers of people. ... ... Some epidemiologists concentrate on communicable diseases, like tuberculosis and AIDS. Others focus on the growing epidemics in cancer, diabetes, and heart disease. We gather data in a variety of ways. One way is through what we call descriptive epidemiology, or looking at the trends of disease over time, as well as ... uh ... trends of diseases in one population relative to another. (Hi, everybody! What does "relative" mean in this context? I found two definitions for "relative" in the dictionary - 1)considered by being compared with sth. else. 2) connected with something. I can not figure out which definition is suitable for this sentence, which just means I can not get the meaning of this sentence - trends of diseases in one population relative to another. What is your opinion? )

Thanks for your help !

[David L.]

...trends of diseases in one population relative to another.

...trends of diseases in one population compared to another.

Hence, definition (i).