The Sr-doped neodymium nickelates have similar (K₂NiF₄-type) structures both to the high-T_c superconductor La_1.85Sr_0.15CuO₄ and to La_2-xSr_xNiO₄ materials, in which anomalous diamagnetic signals have been observed. The authors have made AC-susceptibility, oxygen content, XRD and resistance measurements on Nd_2-xSr_xNiO_{4+ delta} samples for a wide range of Sr doping levels (0<or=x<or=1.30). Metal semiconductor transitions occur below room temperature in samples with a high Sr concentration (x>or=0.90) while more subtle changes in the nature of the electrical conductivity occur in the low-temperature resistance of samples with lower doping levels. These changes in resistance with doping and temperature are closely associated with changes in structure and with the strength of the Ni ion magnetic interactions. Similar changes in resistivity occur in the La_2-xSr_xCuO₄ system, although over a much narrower range of Sr doping levels than in the nickelates.