Low serum levels of cholesterol have been associated with depression. (This is true! I didnot make this up. It is not clear why, but I like to think that ice cream deprivation may be
an explanation ?- :) - JEF) Based on this observation, investigators conducted a study to
examine the association of serum cholesterol levels and suicide. They used a database
from a health maintenance organization to identify persons who had normal cholesterol
and persons who had high cholesterol levels identified by their physician at least 10
years ago. The investigators then linked this information to the National Death Index to
identify persons who had later died by suicide. What type of study was this?