Table 3.

Variables chosen for analysis, their contextual relevance, and sources

Variable	Data source
Individual and population
Enabling/disabling	Developed from linked California SEER cancer registry and Medicare data, provided by the National Cancer Institute, 2000–2003
Individual disability or ESRD as original reason for Medicare entitlement
Moved to a new ZIP code in same state, 2000–2002 or 2003–2005
Months with extra assistance from state Medicaid (dual eligibility), 2000–2002 or 2003–2005
Distance to closest endoscopy facility
Predisposing
Age in 2000
Months enrolled in a Medicare HMO anytime in 2000–2002 or 2003–2005
Enrollment in Medicare HMO during the past 2 years
Race or ethnicity (white, African American, Asian, Hispanic, Native American, other)
Need
Had previous cancer diagnosis, breast or colorectal; had irritable bowel disease
Interpersonal factor (PCSA)
Social integration and support: isolation index describing segregation by race or ethnicity (white, African American, Asian, Hispanic, Native American, other), 2000	Developed from U.S. Census 2000 data at ZCTA levels aggregated to PCSAs using HRSA's crosswalk: http://datawarehouse.hrsa.gov/
Stressor, driver courtesy: commuter intensity reflecting the proportion of the workforce in each person's residential area commuting 60 min or more each way to work
Social or cultural cohesion: proportion of the elderly in each person's residential area with little or no English language ability, 2000
Local health norms and behaviors: Medicare managed care penetration, defined as proportion of the eligible population enrolled in Medicare managed care plans: 2001; 2004	Built by RTI from 100% beneficiary denominator files provided by the Centers for Medicare & Medicaid Services
Intermediate/community factor (county)
Proportion of population living below the federal poverty level; GINI coefficient of household income disparity (calculated by RTI)	Census annual poverty estimates; census 2000 household income estimates
Health care system: number of endoscopy facilities per thousand elderly in each person's residential area, 2000–2002, 2003–2005	SEER-Medicare linked data and U.S. Census
Health care system: number of oncologists (2000, 2003), gastroenterologists (2000, 2003), or nurses (2000, 2005) per thousand elderly (2000, 2003)	Area resource file; annual census population estimates

SEER surveillance, epidemiology, and end results, ZCTA ZIP code tabulation area, HRSA health resources and services administration, PCSA primary care service area