Film historians describe stag films as a primitive form of cinema because they were produced by anonymous and amateur male artists who generally failed in achieving narrative coherence and continuity. Today, many of these films have been archived by the Kinsey Institute; however, most stag films are in a state of decay and have no copyright, credits, or acknowledged authorship. The stag film era ended due to the beginnings of the sexual revolution in the 1950's in combination with the new visual technologies of the post-war era, such as 16 mm, 8 mm, and Super 8 film. Scholars at the Kinsey Institute believe there are approximately 2000 films produced between 1915 and 1968.