writes:

Two orders of magnitude means 100 times.

Yes, I know.

The GPS specification with SA on is 100 m lateral, 150 m vertical, which
is 1.5 times.

SA has been off for years.

GPS measured accuracy with SA off is 2.5 m lateral, 4.7 m vertical, which
is 1.9 times.

The vertical accuracy is far worse than 4.7 metres.

It looks as though we can add GPS and simple arithmetic to the list of
things which you pontificate about yet know nothing about.

Be sure to fly IFR sometime in IMC with GPS as your altimeter, and you'll see
what I mean.