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Assessment of the Impact of Receiving Eyeglasses on Productivity in Handicraft Weaving in Rwanda
Last registered on December 20, 2013


Trial Information
General Information
Assessment of the Impact of Receiving Eyeglasses on Productivity in Handicraft Weaving in Rwanda
Initial registration date
Not yet registered
Last updated
December 20, 2013 2:09 PM EST
Primary Investigator
University of Minnesota
Other Primary Investigator(s)
PI Affiliation
Tufts University
Additional Trial Information
On going
Start date
End date
Secondary IDs
In developing countries, most low income families obtain almost all of their income from working, and remain in poverty primarily because they can earn only low wages and low incomes in self-employment. One relatively simple policy that has the potential to increase incomes for certain types of workers is the provision of eyeglasses. Many adults in developing countries work in handicraft production, and many of them require adequate eyesight to produce handicraft items in sufficient quantity and quality. As these workers get older, their vision typically deteriorates. One common problem is hyperopia, which is more commonly called farsightedness. Older adults with hyperopia lose their ability to focus on objects that are very near to them. They lose their ability to read books and other documents and, more generally, experience a reduction in their ability to do any work for which they must focus on objects that are less than 1-2 meters from their eyes. Almost all types of hyperopia can be corrected with simple reading glasses, yet in many developing countries the use of any kind of eyeglasses is rare, especially among the poor. This randomized control trial (RCT) investigates the impact on worker productivity of providing reading glasses to adults who have developed hyperopia. More specifically, it focuses on Rwandan women in weaving cooperatives who make baskets, earrings, and other handicraft objects from grasses, reeds and other natural fibers. Weaving productivty (in terms of both quantity and quality) was directly measured under conditions designed for minimum distraction.
External Link(s)
Registration Citation
Glewwe, Paul and Julie Schaffner. 2013. "Assessment of the Impact of Receiving Eyeglasses on Productivity in Handicraft Weaving in Rwanda." AEA RCT Registry. December 20. https://doi.org/10.1257/rct.161-1.0.
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Experimental Details
Providing reading glasses to handicraft weavers who are farsighted (hyperopia).
Intervention Start Date
Intervention End Date
Primary Outcomes
Primary Outcomes (end points)
Speed in making earring set. Quality of earring set. Value per minute of time spent weaving.
Primary Outcomes (explanation)
Secondary Outcomes
Secondary Outcomes (end points)
Secondary Outcomes (explanation)
Experimental Design
Experimental Design
Eight groups, each with about 30 women handicraft weavers, were randomly assigned to treatment or control groups (4 treatment and 4 control). Baseline data on weaving productivity were collected at the end of September 2013. Vision tests were given to all women. Those in the treatment group with hyperopia were offered reading glasses, and all accepted. About 2 weeks later their productivity was measured again, and at the end the control group women with hyperopia were offered reading glasses.
Experimental Design Details
Randomization Method
Coin flip
Randomization Unit
Groups of about 30 basket weavers
Was the treatment clustered?
Experiment Characteristics
Sample size: planned number of clusters
Sample size: planned number of observations
Sample size (or number of clusters) by treatment arms
Four treatment clusters (about 30 women each) and four control clusters (about 30 women each)
Minimum detectable effect size for main outcomes (accounting for sample design and clustering)
IRB Name
Tufts University IRB
IRB Approval Date
IRB Approval Number
Post Trial Information
Study Withdrawal
Is the intervention completed?
Is data collection complete?
Data Publication
Data Publication
Is public data available?
Program Files
Program Files
Reports and Papers
Preliminary Reports
Relevant Papers