Media expenses are among the most challenging business metrics to measure and monitor. Minor adjustments in mix or vendor selection can lead to concealed cost increases, and underperformance in one area can easily be offset by overperformance in another, masking inefficiencies. Advertisers who make performance audits part of their regular processes improve value and create a media value advantage over time. Ongoing tracking of year-on-year cost trends guards against unchecked rate increases.