Table 1. Data Sources and Record Counts, by Year and Month.
| Source | January | March | ||
|---|---|---|---|---|
|
|
|
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| 1999 | 2000 | 2001 | 2001 | |
| Medicare+Choice Plan Data | ||||
| Number of Plans | 498 | 319 | 352 | 359 |
| Service Area File1 | ||||
| Number of Plan-Counties | 2,755 | 2,543 | 1,801 | 1,825 |
| State/County/Plan File2 | ||||
| Number of Plan-Counties | 33,352 | 33,913 | 28,650 | 28,650 |
| Area Resource File | ||||
| Number of Counties | 3,081 | 3,081 | 3,081 | 3,081 |
| Risk Scores | ||||
| Number of Counties | 3,249 | 3,249 | 3,249 | 3,249 |
1
Includes all managed care plans for 1999 and 2000, while the 2001 files were preprocessed to include only Medicare+Choice (M+C) plans. Ultimately, only M+C plans are retained for analysis (drop non-M+C plans or plans with missing or zero enrollment) so this represents a different sequencing of an otherwise equivalent data processing procedure.
2
Includes plan-county data for all managed care plans and all counties in which they operate.
SOURCES: Centers for Medicare & Medicaid Services: Data from the Medicare Health Plan Compare database, Area Resource File, county-level principal inpatient diagnostic cost groups scores, and Quarterly State/County/Plan File: January 1999, 2000, 2001, and March 2001.