Last week, the Employers Pension Forum published “Proposed Changes to USS – Myths, Misconceptions and Misunderstandings”. The document contains misinformation and a mistake. We focus on the section “M7: The assumptions used to value the fund have been chosen to artificially create a large deficit”.

Having reviewed the assumptions given in the 2013 annual report, we believe, as statisticians and financial mathematicians, that each assumption is inadequately justified and that cumulatively they are unreasonably pessimistic and incoherent. The predicted salary increases assume a buoyant economy while investment returns assume a recession.

For example, the average annual rate of return on assets achieved by the Universities Superannuation Scheme over the past 10 years was about 7 per cent and over the past five years about 11 per cent. It is therefore difficult to understand the EPF’s assertion that “since 2011…the continuing global economic challenges…have had a detrimental impact on the value of USS’ assets”.

Meanwhile, members’ wages are assumed to grow by the retail price index plus 1 per cent (taken to be 4.4 per cent) plus incremental increases. Over the past 20 years the actual rate was about 2.7 per cent, with similar growth over the past 10 years. Post-2008 rates show negative real-pay growth. The age-related assumption is wage growth (1 per cent to 4 per cent) by progress up the salary scale: anecdotally this assumption leads to higher pay growth rates than the majority of academics have experienced over the past 10 or 20 years. As the fund’s actual experience was used to give a mean retirement age of 62 years at the last valuation, it seems odd that salary assumptions do not also reflect actual experience.

The assumptions on mortality appear to be unchanged from the 2011 valuation, yet the EPF archly advances the statement that “members of the USS are living longer so the pension scheme has to pay pensions in retirement for longer than planned” as a reason for deterioration in the fund’s position since 2011.

A reasonable change in any one of these assumptions would give a lower estimated deficit. The EPF states that although changing the assumptions in this instance could affect the size of the deficit, “it cannot change a deficit into a surplus”. It takes little mathematical knowledge to recognise that this statement is wrong.

Saul Jacka, professor of statistics, University of Warwick
Peter Green FRS, professor emeritus of statistics, University of Bristol
Steven Haberman FIA, dean, Cass Business School
Jane Hutton, department of statistics, University of Warwick
John Aston, professor of statistics, University of Cambridge
Sir David Spiegelhalter FRS, Winton professor of the public understanding of risk, University of Cambridge
Charles Taylor, professor of statistics, University of Leeds
Simon Wood, professor of statistics, University of Bath
Qiwei Yao, professor of statistics, London School of Economics
Michalis Zervos, professor of mathematics, London School of Economics