Amazon systematically attempts to push out 6% of its office employees every year by relying on a series of complex algorithms as well as a controversial management practice that grades employees against one another rather than against their job description or workplace goals, according to a report.

Internal documents obtained by the Seattle Times show the extent to which the online behemoth’s processes closely resemble the practice of stack ranking despite the company strongly denying it. The documents also highlight how much of Amazon’s human resource processes are reliant on proprietary software, apps, and algorithms and provide a glimpse into how the company uses performance improvement plans to funnel low-ranked employees out the door.