This approach has generally developed furthest away from the older ‘big book’ thesis in the more technical and mathematical social sciences. Here the main way of advancing knowledge is a relatively short article (of 8000 words or less) in a refereed professional journal. Writing whole books has long been very uncommon in mathematical and technically based disciplines and it is less important in terms of communicating new research than authoring journal articles. In these disciplines research books have tended to decrease in numbers while journals have boomed. And book authoring has become more of a mid-life and later years professional activity, rather than being associated with the doctorate. Even in British-and European-influenced university systems, therefore, a papers model PhD thesis has become common in the more technical social sciences.