Legalizing Informal Mining in Colombia: Impediments and Implications

Last registered on January 11, 2021


Trial Information

General Information

Legalizing Informal Mining in Colombia: Impediments and Implications
Initial registration date
January 11, 2021

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 11, 2021, 12:13 PM EST

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


Primary Investigator


Other Primary Investigator(s)

PI Affiliation
Emory University

Additional Trial Information

On going
Start date
End date
Secondary IDs
More than 60% of global employees work in the informal economy. One of the reasons that firms remain in informality is the length and cost of the formalization process, with uncertain benefits. We explore a treatment that could reduce informality in the mining sector in Colombia, a segment of the economy that supports more than 300,000 workers and their families. The treatment addresses the supply side with assistance with the formalization process.
External Link(s)

Registration Citation

Saavedra, Santiago and Renard Sexton. 2021. "Legalizing Informal Mining in Colombia: Impediments and Implications." AEA RCT Registry. January 11.
Experimental Details


The treatment provides assistance with the formalization process.
Intervention Start Date
Intervention End Date

Primary Outcomes

Primary Outcomes (end points)
Formalization dummy
In-process of formalization dummy
Number of workers
Quantity produced
Sell price
Operational costs
Primary Outcomes (explanation)

Secondary Outcomes

Secondary Outcomes (end points)
Total income
Mining income

\item Interactions with police, including bribes, coercion
\item Interactions with armed groups or organized crime
\item Interactions with nearby landowners
\item Interactions with government agents

\item Pollution levels in rivers nearby each mine
\item Health conditions in area surrounding mine
Secondary Outcomes (explanation)
Interactions collected on endline questionnaire

Experimental Design

Experimental Design
Sampling of eligible municipalities was done based on several characteristics:

\item Mining zones in areas still affected by significant armed conflict or armed groups were excluded
\item Gold and coal areas were prioritized: Antioquia and Chocó are the principal departments for gold mining activities, while Boyacá is one of the principals for coal mining.
\item From a government database that registers mines that are in formalization process, we selected municipalities that above 10 requests.

In the end, we selected 38 municipalities in the aforementioned 3 Colombian departments (states): 21 in Antioquia, 9 in Boyacá and 8 in Chocó. The final list was slightly different than the original one because as it turned out, we could not visit one municipality in Antioquia and four municipalities in Chocó due to a greater risk of armed conflict than we expected ex-ante.

After reviewing the baseline information, we selected 229 mines that the final experimental sample using the following criteria:


\item Exclude 30 mines that do not mine coal or gold. The reason corresponds to the small quantity of mines extracting this mineral.
\item Exclude 7 mines whose work area is above 150 hectares. This criteria corresponds to the fact that mine titles, whose area is above 150 hectares, are not considered as small-scale mines by the Colombian Law. Because most of mines in our baseline do not have a title, we use work area as our criterion.


This yields a sample of 229 mines in 38 municipalities. Table \ref{sample} presents the distribution of these mines according to mineral mined and formalization status. Of the 229 artisanal mines in the sample, 68 are already formalized, mostly in the coal sector. This leaves us with 151 mines that are not formal and could benefit from treatment.

We will assign two thirds of the 151 mines to treatment using a stratified randomization. We stratify mines using the following criteria: mineral type, department ,formalization status and area size (small/large). We merge small groups with no more than two units, leaving us with 11 groups.
Experimental Design Details
Not available
Randomization Method
Randomization done in office with Stata. The seed for the random number generator will be the score of the Alabama-OSU football game of Jan 11th 2021.
Randomization Unit
Was the treatment clustered?

Experiment Characteristics

Sample size: planned number of clusters
151 mines
Sample size: planned number of observations
151 mines
Sample size (or number of clusters) by treatment arms
97 mines assigned to treatment and 54 to the control group. Two-thirds assigned to treatment in each stratification group, rounding up for the control.
Minimum detectable effect size for main outcomes (accounting for sample design and clustering)
Supporting Documents and Materials

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Institutional Review Boards (IRBs)

IRB Name
Emory University Institutional Review Borad
IRB Approval Date
IRB Approval Number