The impact of refractive error correction on harvest workers in the Guatemalan coffee sector

Last registered on January 20, 2025

View Trial History

Pre-Trial

Trial Information

General Information

Title

The impact of refractive error correction on harvest workers in the Guatemalan coffee sector

RCT ID

AEARCTR-0012852

Initial registration date

January 17, 2024

Initial registration date is when the trial was registered.

It corresponds to when the registration was submitted to the Registry to be reviewed for publication.

First published

January 19, 2024, 2:18 PM EST

First published corresponds to when the trial was first made public on the Registry after being reviewed.

Last updated

January 20, 2025, 10:49 PM EST

Last updated is the most recent time when changes to the trial's registration were published.

Locations

Country

Guatemala

Region

Primary Investigator

Name

Andrew Hobbs

Affiliation

Contact Primary Investigator

Other Primary Investigator(s)

PI Name

Bryce Everett

PI Affiliation

Contact Investigator

PI Name

Bruce Wydick

PI Affiliation

PI Name

Travis Lybbert

PI Affiliation

PI Name

Kevin Frick

PI Affiliation

PI Name

Brad Wong

PI Affiliation

Additional Trial Information

Status

Completed

Start date

2023-12-01

End date

2024-06-30

Keywords

Agriculture, Health

Additional Keywords

JEL code(s)

Secondary IDs

Prior work

This trial does not extend or rely on any prior RCTs.

Abstract

The purpose of this research is to measure the impact of vision correction on the productivity of harvest workers in the Guatemalan coffee sector.

External Link(s)

Registration Citation

Citation

Everett, Bryce et al. 2025. "The impact of refractive error correction on harvest workers in the Guatemalan coffee sector." AEA RCT Registry. January 20. https://doi.org/10.1257/rct.12852-2.0

Sponsors & Partners

Experimental Details

Interventions

Intervention(s)

Intervention (Hidden)

Intervention Start Date

2023-12-21

Intervention End Date

2024-03-31

Primary Outcomes

Primary Outcomes (end points)

Coffee cherries harvested (measured by weight).

Primary Outcomes (explanation)

Secondary Outcomes

Secondary Outcomes (end points)

Secondary Outcomes (explanation)

Experimental Design

The purpose of this research is to measure the impact of vision correction on the productivity of harvest workers in the Guatemalan coffee sector. Productivity will be measured as the daily quantity of cherries picked during the harvest season. Secondary outcomes include measures of worker wellbeing, optimism and aspirations.

Experimental Design Details

Randomization Method

Done by a computer

Randomization Unit

Individual

Was the treatment clustered?

Experiment Characteristics

Sample size: planned number of clusters

Treatment is not clustered.

Sample size: planned number of observations

1000-2000

Sample size (or number of clusters) by treatment arms

Depends on the share of individuals who need corrective lenses (see pre-analysis plan for more details).

Minimum detectable effect size for main outcomes (accounting for sample design and clustering)

Supporting Documents and Materials

Documents

Document Name

Amendment 1

Document Type

other

Document Description

Some changes were made to our analysis plan due to conditions in the field. This plan was filed on February 27, 2024, before post-treatment data was received.

File

Amendment 1

MD5: 8f160d6110df9a1f1222e0d704b8cb70

SHA1: fb9dedcc15c331fa64e704447b025a1ea33ef6fc

Uploaded At: February 27, 2024

Document Name

Amendment 2

Document Type

other

Document Description

Some changes were made to our analysis plan to include an additional refractive error diagnosis with a higher prevalence than anticipated and to correct a model specification error. This plan was filed on January 21, 2025, after data collection had concluded.

File

Amendment 2

MD5:

SHA1:

Uploaded At: January 20, 2025

IRB