Probability and significance

Statistical table

A grid of the critical values required for significance to be achieved for any particular statistical test

Critical value

When testing a hypothesis, the numerical boundary or cut-off point between acceptance and rejection of the null hypothesis

Probability

A measure of the likelihood that a particular event will occur where 0 indicates statistical impossibility and 1 is statistical certainty

Significance

A statistical term that tells us how sure we are that a difference or correlation exists.

A ‘significant’ result means that the researcher can reject the null hypothesis

Type 1 error

The incorrect rejection of a true null hypothesis

False positive

Type 2 error

The failure to reject a false null hypothesis

False negative