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Study Overview

Replication of Bleakley 2007
Study is 3ie funded:
Study ID:
Initial Registration Date:
Last Update Date:
Study Status:
In Development

We plan to replicate Bleakley, 2007 including re-collection of all data from original sources outlined in the paper and re-creation of as many of the conducted analyses as possible.

Registration Citation:

Roodman, D., 2018. Replication of Bleakley 2007. Registry for International Development for Impact Evaluations (RIDIE). Available at: 10.23846/ridie139

Health, Nutrition, and Population
Additional Keywords:
Bleakley 2007, replication
Secondary ID Number(s):

Principal Investigator(s)

Name of First PI:
David Roodman
Name of Second PI:

Research Partner

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Type of Organization:

Intervention Overview


This study evaluates the economic consequences of the successful eradication of hookworm disease from the American South, which started circa 1910. The Rockefeller Sanitary Commission (RSC) surveyed infection rates and found that 40 percent of school-aged children in the South were infected with hookworm. The RSC then sponsored treatment and education campaigns across the region. We aim to re-investigate the conclusions of the Bleakley 2007 study as it is the most complete long term study of de-worming to-date. The results of this paper are instrumental to our understanding of the potential impacts of de-worming campaigns currently underway.

Theory of Change:
Multiple Treatment Arms Evaluated?

Implementing Agency

Name of Organization:
The Rockefeller Sanitary Commission 1910-1915
Type of Organization:
NGO (local)/Community Based Organization/Other civil society organization

Program Funder

Name of Organization:
The Rockefeller Sanitary Commission 1910-1915
Type of Organization:
NGO (local)/Community Based Organization/Other civil society organization

Intervention Timing

Intervention or Program Started at time of Registration?
Start Date:
End Date:
Evaluation Method

Evaluation Method Overview

Primary (or First) Evaluation Method:
Regression discontinuity
Other (not Listed) Method:
Additional Evaluation Method (If Any):
Instrumental variables
Other (not Listed) Method:

Method Details

Details of Evaluation Approach:

We will attempt to match as many published tables and graphs in the original as possible. Exceptions for reasons of data availability may include Panel B of Table III, the second half of Figure III, and the “Full controls” rows of Table VI. If any mismatches arise, which is to be expected, we will seek to work with Hoy Bleakley to narrow or explain them. Additional analyses may include: testing for sensitivity to any data or coding errors exposed in the original; performing two-stage least squares instead of the original’s indirect least squares in order to obtain proper confidence intervals for instrumental variables point estimates; pure time-series versions of the sequential cross-sections (SCS) analysis, in which samples are restricted to areas of above-average baseline prevalence, and the intent-to-treat variable is years of exposure to the deworming campaign (Expik) rather than the interaction thereof with baseline prevalence; more-conservative error-clustering choices, such as clustering county-level estimates by state rather than State Economic Area; and re-doing the two-stage assessment of whether the hookworm campaign helps explain the convergence in long-term earnings be

Outcomes (Endpoints):

We are looking at short term outcomes in school enrollment, attendance, literacy and long term income effects

Unit of Analysis:
We are looking at county and state level results in the USA, as well as SEA (State Economic Area) as the data are available. Analysis will be grouped by birth-year.
Unit of Intervention or Assignment:
Observations are naturally assigned based on prevalence of hookworm infection pre-treatment.
Number of Clusters in Sample:
550 year/state clusters (every census period from 1880-1990 across 50 states), 600 counties where treatment was administered.
Number of Individuals in Sample:
Total sample will include the population of the Southern United States circa. 1910 in 11 states based on the US Census data.
Size of Treatment, Control, or Comparison Subsamples:
NA, treatment and control are based on intensity of infection in a given county or state, not treatment/control assignment

Supplementary Files

Analysis Plan:
Replication of Bleakley 2007.pdf
Other Documents:

Outcomes Data

Data will be collected according to the paper by Bleakley 2007. Mostly from the Rockefeller Sanitary Commission, the IPUMS Census data, ICPSR study 3, and various reports from the department of education.
Data Already Collected?
Data Previously Used?
Data Access:
Not restricted - access with no requirements or minimal requirements (e.g. web registration)
Data Obtained by the Study Researchers?
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Treatment Assignment Data

Participation or Assignment Information:
Data Obtained by the Study Researchers?
Data Previously Used?
Data Access:
Data Obtained by the Study Researchers?
Data Approval Process:
Approval Status:

Data Analysis

Data Analysis Status:

Study Materials

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Registration Category

Registration Category:
Prospective, Category 3: Data for measuring impacts have been obtained/collected by the research team but analysis for this evaluation has not started

Completion Overview

Intervention Completion Date:
Data Collection Completion Date:
Unit of Analysis:
Clusters in Final Sample:
Total Observations in Final Sample:
Size of Treatment, Control, or Comparison Subsamples:


Preliminary Report:
Preliminary Report URL:
Summary of Findings:
Paper Summary:
Paper Citation:

Data Availability

Data Availability (Primary Data):
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Data URL or Contact:
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Other Materials

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Program Files:
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External Link:
External Link Description:
Description of Changes:

Study Stopped