The global rates describes the profile of a
population in terms of the prevalence of mortality or
morbidity. The numerator indicates the number of
total success and the denominator is the total
episodes that could be occurs. They are expressed
per thousands (fetal mortality rate, early neonatal
rate etc. ) or per a hundred of thousands (maternal
rate).

The specific rates shown the frecuency of adverse
results for specifics groups of the population. The
numerator indicates the success according to the
variable considered and the denominator is the total
of subjects that are in that group, for a defined time
and place.

Risk: it means that specific groups have more
probability to get an adverse result. The rate used
depends on the type of study: Case-control or
cohorts.