That changes over time. Nobel's intention was to give it to people that gave the greatest benefit to mankind during the year. A few prices in the later years have been directed toward less base-research like inventions.
Also... why do people keep refering to the "The Sveriges Riksbank Prize in Economic Sciences in Memory of Alfred Nobel" as a nobel prize in economics? It's not one of the subjects that Nobel himself thought worthy.
Indeed, if you look at the very earliest Nobel prizes they were less focused on basic research. For example, the 1909 Physics prize to Marconi/Braun "in recognition of their contributions to the development of wireless telegraphy" or the 1912 Physics prize to Gustaf Dalen "for his invention of automatic regulators for use in conjunction with gas accumulators for illuminating lighthouses and buoys".
Also... why do people keep refering to the "The Sveriges Riksbank Prize in Economic Sciences in Memory of Alfred Nobel" as a nobel prize in economics? It's not one of the subjects that Nobel himself thought worthy.