Subjects and diseases

Some names of subjects and diseases, which appear to be plural because they end in ‑s, are normally used as singular. These include:

acoustics
aeronautics
dynamics
economics
electronics
ergonomics
ethics
forensics
genetics
hydraulics
linguistics
mathematics
obstetrics
optics
paediatrics GB or pediatrics US
phonetics
physics
politics
robotics
semantics
semiotics
statistics
tectonics

And

diabetes
measles
mumps
rabies
rickets
scabies
shingles

Also

news

Examples

Economics is taught at many universities.
Linguistics is the study of language.
Obstetrics is a branch of medicine.
Politics is a dirty business.
Diabetes is a growing problem.
The news about Dolly was a great surprise.

Exceptions

There are some exceptions when the word denotes not the name but rather the application of the subject. It may then be used as plural, for example:

Good acoustics are important.
Economics dictate many aspects of our lives.
His politics are well known.
These statistics are unreliable.

And a form without ‑s can occur in some words:

A strong work ethic
One statistic worth noting is that …
A common tactic