What is merits review?

The Administrative Appeals Tribunal explains merits reviews as:

'…to reconsider the decision under review and determine whether it is the correct and preferable decision. Correct, when there is only one decision; preferable, when a range of decisions is available. … Merits review has been said to involve the administrative review tribunal 'standing in the shoes' of the original decision–maker.'

From 'Tribunals in Australia: Their Roles and Responsibilities'. Published in the Australian Law Reform Commission's Journal Reform Issue 84, Autumn 2004.