Attrition in Randomized Control Trials: Using Tracking Information to Correct Bias

Teresa Molina Millan () and Karen Macours

No 10711, IZA Discussion Papers from Institute of Labor Economics (IZA)

Abstract: This paper starts from a review of RCT studies in development economics, and documents many studies largely ignore attrition once attrition rates are found balanced between treatment arms. The paper analyzes the implications of attrition for the internal and external validity of the results of a randomized experiment with balanced attrition rates, and proposes a new method to correct for attrition bias. We rely on a 10-years longitudinal data set with a final attrition rate of 10 percent, obtained after intensive tracking of migrants, and document the sensitivity of ITT estimates for schooling gains and labour market outcomes for a social program in Nicaragua. We find that not including those found during the intensive tracking leads to an overestimate of the ITT effects for the target population by more than 35 percent, and that selection into attrition is driven by observable baseline characteristics. We propose to correct for attrition using inverse probability weighting with estimates of weights that exploit the similarities between missing individuals and those found during an intensive tracking phase. We compare these estimates with alternative strategies using regression adjustment, standard weights, bounds or proxy information.

Keywords: survey non response; sample selectivity; randomized controlled trial; inverse probability weights (search for similar items in EconPapers)
JEL-codes: C52 C93 O1 (search for similar items in EconPapers)
Pages: 85 pages
Date: 2017-04
New Economics Papers: this item is included in nep-exp and nep-lab
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (19)

Downloads: (external link)
https://docs.iza.org/dp10711.pdf (application/pdf)

Related works:
Working Paper: Attrition in Randomized Control Trials: Using tracking information to correct bias (2017)
Working Paper: Attrition in randomized control trials: Using tracking information to correct bias (2017)
This item may be available elsewhere in EconPapers: Search for items with the same title.

Export reference: BibTeX RIS (EndNote, ProCite, RefMan) HTML/Text

Persistent link: https://EconPapers.repec.org/RePEc:iza:izadps:dp10711

Ordering information: This working paper can be ordered from
IZA, Margard Ody, P.O. Box 7240, D-53072 Bonn, Germany

Access Statistics for this paper

More papers in IZA Discussion Papers from Institute of Labor Economics (IZA) IZA, P.O. Box 7240, D-53072 Bonn, Germany. Contact information at EDIRC.
Bibliographic data for series maintained by Holger Hinte ().