HARRISBURG (AP) – The board of PA’s largest public pension system – the Public School Employees’ Retirement System – said it’s investigating a consultant’s calculation about the fund’s investment performance last year that is apparently wrong. The calculation was slightly above a 6.36% growth threshold, thus protecting retirement system members from a higher risk-sharing contribution rate. But on March 12, the PSERS board issued a brief statement saying it had been made aware of an error in the calculation. On Friday, it said it was investigating the circumstances regarding the calculation and actions taken by PSERS’ staff and the consultant after the disclosure. On Dec. 31, PSERS reported net assets of $64.2 billion.