The correct answers are: Non-statistical sampling methods are more prone to bias than statistical sampling methods; Statistical sampling methods can give precise, quantifiable results in relation to the population from which the sample is drawn.

Non-statistical sampling methods are more prone to bias than statistical sampling methods because statistical sampling methods do not permit the use of judgement in the selection of the items to be tested in the same way as non-statistical methods. Nevertheless, properly applied non-statistical methods are acceptable. Statistical sampling methods can give a precise, quantifiable result in relation to the population from which the sample is drawn (e.g. they can state that there is an x% likelihood that the population lies within plus or minus y% of the value stated).

Auditing standards do not discourage the use of non-statistical sampling methods, although they recognise the advantages and disadvantages of both statistical and non-statistical sampling. Statistical sampling does not necessarily result in smaller samples than non-statistical sampling and statistical sampling never eliminates the need for the use of professional judgement in evaluating sample results.