This weeks The Economist features an article on the productive effects of eyeglasses - a topic closely related to my own work. In the article the authors refer to a randomized control trial (RCT) by a group of researchers from Queen’s University Belfast who found that providing eyeglasses to tea pickers with presbyopia in India increases their productivity by 39% (article here). For the tea pickers this translates into a direct income gain. While these high productivity gains might be feasible for tea pickers, other studies and also my own work suggest that productive effects might be more modest. Assessing the productivity of basket weavers in Rwanda Paul Glewwe from the University of Minnesota and Julie Schaffner from Tufts find only limited evidence for productivity improvements (article here). Observational data from our own work on the provisioning of eyeglasses in rural Burkina Faso among subsistence farmers would point at more modest effects. While in the baseline survey participants reported that they expect improvements in the quality and speed of work and in consequence also in working hours and income, the follow-up survey conducted six months after the glasses have been distributed shows a clear decline in these initial expectations. In our case, few participants reported increases in labor hours - the average for those reporting a positive increase however is sizeable at 4.3 hours per week. However, only in a few cases is the increase in work hours also associated with an increase in weekly earnings. One impediment in our context is certainly that the study participants are wearing the glasses worn in select situations - for reading, when traveling or in church but not for or during work.
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