Despite dozens of trials into four-day working weeks, there is still little evidence about their impact. In 2022, 61 U.K. businesses experimented with giving employees an extra day off each week. Of those, 54 continued the pattern after the trial ended. But a policy researcher told the Financial Times that, despite apparent benefits for wellbeing and staff retention, few conclusions could be drawn, because the trial was poorly designed: The companies were self-selecting rather than randomized, and there was no control group to see what would have happened without the change. Trials of policy rarely include what scientists would consider very basic experimental design standards, but without them the evidence for or against a policy will always be weak. |