Table 1.

Hypothetical patients and counterfactual example.

2008	MS-DRG (Post 2007)	MS-DRG Weight	CMS-DRG (2007 and before)	CMS-DRG Weight	Change in Weight
Patient 1	200	1.3	124	1.21	.09
Patient 2	200	1.3	124	1.21	.09
Patient 3	200	1.3	124	1.21	.09
Patient 4	201	1.12	124	1.21	−.09
Patient 5	201	1.12	124	1.21	−.09
Patient 6	201	1.12	124	1.21	−.09
Average Change in weight:					0

Notes: This table illustrates for 6 hypothetical patients how, in the absence of upcoding, we would not expect a change in average DRG weight. The column titled MS-DRG weight shows the weight associated with the new DRG post reform. The CMS-DRG weight column shows the DRG the patient would have been assigned if they had been admitted prior to the DRG expansion. The CMS-DRG Weight column shows the weight associated with the CMS-DRG. The column Change in Weight is the difference between MS-DRG Weights and CMS-DRG Weights. The Change in Weight column highlights that in the refinement of DRGs, some patients would be less sick than the average patient in the CMS-DRG, and thus would have negative weights post-reform. Other patients would be sicker than the average patient in the CMS-DRG, and would have a higher weight post-reform.