Preschool classmates during elementary school

Last registered on July 23, 2026
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Pre-Trial

Trial Information

General Information

Title
Preschool classmates during elementary school
RCT ID
AEARCTR-0019227
Initial registration date
July 22, 2026

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
July 23, 2026, 8:32 AM EDT

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

Locations

Country
United States of America
Region

Primary Investigator

Name
Haruka Uchida
Affiliation
University of Chicago
Contact Primary Investigator

Other Primary Investigator(s)

PI Name
John List
PI Affiliation
University of Chicago
Contact Investigator

Additional Trial Information

Status
Completed
Start date
2010-01-01
End date
2019-12-31
Keywords
Education
Additional Keywords
JEL code(s)
Secondary IDs
Prior work
This trial is based on or builds upon one or more prior RCTs.
Abstract
This study examines whether the effects of the Chicago Heights Early Childhood Center preschool on cognitive skill outcomes during elementary school are affected by exposure to classmates (during elementary school) who also attended the preschool.
External Link(s)

Registration Citation

Citation
List, John and Haruka Uchida. 2026. "Preschool classmates during elementary school." AEA RCT Registry. July 23. https://doi.org/10.1257/rct.19227-1.0
Sponsors & Partners
Experimental Details

Interventions

Intervention(s)
We use a pre-existing randomized controlled trial (e.g. Fryer, Levitt, and List, 2015; Castillo et al 2024; Chuan et al 2026), called the Chicago Heights Early Childhood Center (CHECC). CHECC randomized 2,185 children aged 3-4 years old (4 cohorts) to a preschool, a Parent Academy workshop, or the control group. Our paper will focus on the preschool and control groups.
Intervention (Hidden)
Intervention Start Date
2010-01-01
Intervention End Date
2014-12-31

Primary Outcomes

Primary Outcomes (end points)
Standardized test scores in math and reading
Primary Outcomes (explanation)

Secondary Outcomes

Secondary Outcomes (end points)
Secondary Outcomes (explanation)

Experimental Design

Experimental Design
We use a pre-existing randomized controlled trial (e.g. Fryer, Levitt, and List, 2015; Castillo et al 2024; Chuan et al 2026), called the Chicago Heights Early Childhood Center (CHECC). Between 2010-14, CHECC randomized 2,185 children aged 3-4 years old (4 cohorts) into one of several programs, and this study will focus on the Preschool and Control groups. All children ages 3-4.99 (as measured on September 1 of any year) were eligible to sign up, regardless of socio-economic status. The distinction for this study is that it will examine whether the effects of CHECC preschool on cognitive skill outcomes during elementary school are affected by exposure to classmates (during elementary school) who also attended the preschool. This is possible due to the a partnership with Chicago Heights school district, which agreed to randomly allocate students across classrooms during elementary school, irrespective of achievement.
Experimental Design Details
Randomization Method
We use a pre-existing randomized controlled trial (e.g. Fryer, Levitt, and List, 2015; Castillo et al 2024; Chuan et al 2026), called the Chicago Heights Early Childhood Center (CHECC). CHECC randomized 2,185 children aged 3-4 years old (4 cohorts) to a preschool, a Parent Academy workshop, or the control group. Our paper will focus on the preschool and control groups.
Randomization Unit
Family. For families with one child of preschool age in 2010-2014, this will be equivalent to randomizing at the child level. For families with more than one child of preschool age in 2010-2014, all children will be randomized to the same treatment.
Was the treatment clustered?
No

Experiment Characteristics

Sample size: planned number of clusters
2000 CHECC families
Sample size: planned number of observations
2000 CHECC families, corresponding to approximately 2000 children
Sample size (or number of clusters) by treatment arms
1132 in Control; 532 in Preschool
Minimum detectable effect size for main outcomes (accounting for sample design and clustering)
Supporting Documents and Materials
IRB

Institutional Review Boards (IRBs)

IRB Name
University of Chicago Social and Behavioral Sciences Institutional Review Board
IRB Approval Date
2010-05-27
IRB Approval Number
H10083
Analysis Plan

Post-Trial

Post Trial Information

Study Withdrawal

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Intervention

Is the intervention completed?
No
Data Collection Complete
Data Publication

Data Publication

Is public data available?
No

Program Files

Program Files
Reports, Papers & Other Materials

Relevant Paper(s)

Reports & Other Materials