John Snow, author of Snow on Cholera:
was the father of modern biostatistics.
established postulates for transmission of infectious disease.
was an early epidemiologist who used natural experiments.
argued that the environment was associated with diseases such as malaria.

Was an early epidemiologist who used natural experiments.

Explanation:

John Snow was an English physician who is particularly well-known for studying the method of transmission of cholera. He traced the source of a cholera outbreak in Soho, London in 1854. This led to the establishment of modern epidemiology. He was also a leader in the development of anaesthesia and medical hygiene.

the two sonnets of sidney most closely follows the division between the octave and the sestet are the astrophel and stella sonnets.