Building the Evidence Base for the Medical Home: What Sample and Sample Size Do Studies Need?

October 2011
AHRQ Publication No. 11-0100-EF
Prepared For:
Agency for Healthcare Research and Quality, U.S. Department of Health and Human Services, 540 Gaither Road, Rockville, MD 20850,

Contract Number: HHSA290200900019I TO2
Prepared by: Mathematica Policy Research Princeton, NJ; Deborah Peikes, Mathematica Policy Research; Stacy Dale, Mathematica Policy Research; Eric Lundquist, Mathematica Policy Research; Janice Genevro, Agency for Healthcare Research and Quality; and David Meyers, Agency for Healthcare Research and Quality
Table 1. Average coefficient of variation (CV) for continuous variables from studies in our literature review
PopulationCostsHospitalizationsEmergency Room VisitsHospital Days
Source: Estimates compiled by authors. Appendix E provides more details.
Note: n denotes the number of studies that were included in the average for each cell.
NA = not available.
All, Privately Insured3.73 (n=3)4.7 (n=2)2.83 (n=2)NA
Chronically Ill, Privately Insured2.50 (n=2)3.18 (n=2)2.21 (n=2)5.80 (n=1)
All, Medicare2.46 (n=3)3.00 (n=1)2.00 (n=1)5.78 (n=1)
Chronically Ill, Medicare1.64 (n=3)1.99 (n=4)2.75 (n=2)3.07 (n=3)