Type I and type II errors

When testing hypothesis (H₀) and deciding to either reject or accept a null hypothesis, there are four possible happenings.

a) Acceptance of a true hypothesis as correct decision - accepting the null hypothesis and it occurs to be the correct decision.  Note that statistics does not provide absolute information; hence its conclusion could be wrong only that the probability of it being right is high.

b) Rejection of a false hypothesis as correct decision.

c) Rejection of a true hypothesis - (incorrect decision) - it is called type I error, along with probability = α.

d) Acceptance of a false hypothesis - (incorrect decision) - it is called type II error, along with probability = β.