Customers downloading apps using a publisher's promotional code will no longer be allowed to rate them, as Apple shuts down another common source of unfair ratings manipulation.
Although the company has made no official announcement, an Apple customer support email posted on the Touch Arcade forums appears to state the policy that, "It is no longer possible to rate or review an app if it was downloaded using a developer's promotional code."
No reason for the change is given, but it is presumed to be an attempt to stop biased ratings from customers who have received the app for free - and would therefore be likely to have a more favourable opinion.
The move will also prevent reviewers from adding their own ratings, leaving app rankings to be created purely according to feedback from paying customers.
Earlier last month Apple appeared to alter the algorithms used to create chart positions, with a reweighting to take into account not only how many times an app is downloaded but how much it is eventually used.
Again no official announcement of the change was made and it is likely that the alteration in policy regarding promotion codes was made at the same time and has only now been noticed.