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. Author manuscript; available in PMC: 2024 Jan 11.
Published in final edited form as: Am Econ Rev. 2018 Aug;108(8):2048–2087.

Table 6—

Plan Availability: Impact of $50 Increase in Monthly Payments

At least one plan (%) Number of plans HHI
(1) (2) (3) (4) (5) (6) (7) (8) (9)
Δb×2001 −2.04 −3.35 −2.32 0.082 −0.104 0.103 0.001 0.038 −0.002
(1.79) (2.46) (1.78) (0.079) (0.142) (0.082) (0.023) (0.036) (0.023)
Δb×2002 −0.62 −6.57 −0.24 0.079 −0.114 0.092 −0.019 0.015 −0.024
(2.02) (3.13) (2.04) (0.116) (0.191) (0.119) (0.030) (0.046) (0.031)
Δb×2003 3.01 −2.60 3.39 0.124 −0.011 0.139 −0.041 −0.011 −0.048
(2.21) (3.54) (2.23) (0.116) (0.202) (0.119) (0.033) (0.051) (0.033)
Main effects
 County FE X X X X X X X X X
 Year FE X X X X X X X X X
Additional controls Pre-BIPA payment × year FE X X X
Urban × year FE X X X
Pre-BIPA mean of dependent variable 67.5 67.5 67.5 2.39 2.39 2.39 0.57 0.57 0.57
R2 0.86 0.86 0.86 0.70 0.69 0.70 0.73 0.72 0.73

Notes: Table shows coefficients on distance-to-floor × year interactions from difference-in-differences regressions. Although the estimation includes distance-to-floor interactions for all the years in our sample, we display coefficients for the post-reform years (2001–2003) above for brevity. The first-stage results displayed in Table 3 indicate that a $1 change in distance-to-floor translates into a $1 change in the monthly payments, so we can interpret the coefficients as the effect of an increase in monthly payments on a dollar-for-dollar basis. Coefficients are scaled to reflect the impact of a $50 increase in monthly payments. The dependent variables are indicator for at least one plan (columns 1 to 3), number of plans conditional on at least one plan (columns 4 to 6), and Herfindahl-Hirschman Index (HHI) with a scale of 0 to 1 (columns 7 to 9). The sample in columns 1 to 3 is the balanced panel of county-years with nonmissing information on base rates and Medicare beneficiaries during 1997 to 2003. This sample includes 21,504 of 22,001 counties and more than 99.9 percent of all Medicare beneficiaries. The sample in columns 4 to 9 is the unbalanced panel of county-years with at least one MA plan over years 1997 to 2003. This sample includes 4,262 of 22,001 possible county-years and 64 percent of all Medicare beneficiary-years. Year 2000, which is the year prior to BIPA implementation, is the omitted category. Controls are identical to those in Table 3. All monetary values are inflation adjusted to 2000 using the CPI-U. Robust standard errors clustered at the county level are reported in parentheses.