If a company tracks total spending by staff functions – IT, Facilities, HR, and Finance – as a percentage of revenue, then each function can show relative performance over time as a benchmark against the other functions (See my posts of April 9, 2005: finance, IT and HR benchmarks; and Sept. 4, 2005: total spend as a percentage of revenue for staff groups.).
Additionally, to compare changes by function in personnel per thousand employees or internal spending per personnel allows you to benchmark relative performance within a company. The absolute numbers would not be what you report, but changes in ratios. Ratios are key (See my posts of March 12, 2006: librarians to lawyers; Feb. 4, 2007: partner time to other timekeepers’ time; Dec. 22, 2005: compliance and ethics spending to legal spending; June 15, 2005: D&O defense costs to settlements; Sept. 13, 2005: external spend on vendors to law firms.).