what evidence can I use to support the benefits of four-day work week from the study: An important part of their investigation was directed to the arrangement and duration of work including the association between the output of workers and their hours of work, the focus of this paper. The HMWC heard different views on the desirable length of work hours, but they attached significance to the fact that they knew of "no employer who had once adopted the shorter scale of hours ever desires to return to the longer period". In view of the anecdotal information then dominant, the HMWC recognized the value of collecting systematic and meaningful information on the link between the output of workers and their hours of work. To this end, the HMWC commissioned quantitative investigations into the factors affecting the efficiency with which individuals work in the state- controlled munition plants. The HMWC operated for a little over two years and produced 21 Memoranda on activities in munitions plants. Because its findings and recommendations were relevant to workplaces in other industries, shortly after its disestablishment at the end of 1917, a new agency (the Industrial Fatigue Research Board) was formed in July 1918