Section 591.216 - How does OPM combine survey data for the DC area and for COLA areas with multiple survey areas?(a)Washington, DC, area. For each survey item except shelter, OPM averages separately the prices collected in each of the DC survey areas identified in § 591.215(a) and then averages these average prices together using equal weights to compute an overall average by item for the DC area.(b)COLA areas with multiple survey areas. OPM computes weighted average indexes at the item, PEG, MEG, and/or overall level by using the corresponding indexes and Federal employment weights from each survey area within the COLA area. 67 FR 22340 , May 3, 2002, as amended at 69 FR 59763 , Oct. 6, 2004