[en] A formalism is presented to determine donor (N_D) and acceptor (N_A) concentrations in wurtzitic InN characterized by degenerate carrier concentration (n) and mobility (μ). The theory includes scattering not only by charged point defects and impurities, but also by charged threading dislocations, of concentration N_dis. For a 0.45-μm-thick InN layer grown on Al₂O₃ by molecular beam epitaxy, having N_dis=5x10¹⁰ cm^-2, determined by transmission electron microscopy, n(20 K)=3.5x10¹⁸ cm^-3 and μ(20 K)=1055 cm²/V s, determined by Hall effect measurements, the fitted values are N_D=4.7x10¹⁸ cm^-3 and N_A=1.2x10¹⁸ cm^-3. The identities of the donors and acceptors are not known, although a comparison of N_D with analytical data, and also with calculations of defect formation energies, suggests that a potential candidate for the dominant donor is H