[R] acceptable p-level for scientific studies

[Kyriakos Kachrimanis]

Dear list members,

I have a statistical question, that doesn't belong to this list, and I
apologise for that in advance but I would appreciate your help very much.
Is there some convention for selecting the a level for significance testing
in scientific (e.g. chemical processes) studies? Most people use the 0.05
level but I could not find a reference to justify this. Why not 0.01 or 0.1?
Montgomery in his book "Design and Analysis of Experiments" disagrees with
setting a priori acceptable levels at all. Is it necessary to set a limit
for significance testing since R can provide exact probability levels for
the significance of each effect?

Thanks in advance.

Kyriakos Kachrimanis.