Instruction Time, Information, and Student Achievement

Last registered on January 19, 2022


Trial Information

General Information

Instruction Time, Information, and Student Achievement
Initial registration date
January 12, 2022

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, 2022, 10:21 AM EST

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



Primary Investigator

Aarhus University

Other Primary Investigator(s)

PI Affiliation
Aarhus University
PI Affiliation
University of Southern Denmark

Additional Trial Information

Start date
End date
Secondary IDs
Prior work
This trial is based on or builds upon one or more prior RCTs.
We use a randomized controlled trial that combines increased instruction time (a teaching program of two lessons per week in 16 weeks in 5th grade) with information to the teachers about their students’ performance in monthly reading tests. The trial was conducted in grade 5 classrooms in Danish schools in the fall of the school year 2014/15. We find that the intervention improved students’ reading skills. We also find that the intervention reduced teachers’ tendency to underestimate their students’ reading skills (relative to computer-based test scores), that it was most effective for students with underestimated reading skills at baseline, and that these effects were strongest for low-SES students.

External Link(s)

Registration Citation

Andersen, Simon Calmar, Thorbjørn Sejr Guul and Maria Humlum. 2022. "Instruction Time, Information, and Student Achievement." AEA RCT Registry. January 19.
Experimental Details


Intervention Start Date
Intervention End Date

Primary Outcomes

Primary Outcomes (end points)
Reading achievement (as measured by the Danish national tests) at endline
Primary Outcomes (explanation)

Secondary Outcomes

Secondary Outcomes (end points)
Secondary Outcomes (explanation)

Experimental Design

Experimental Design
Schools that had participated in a previous field experiment run by the Ministry of Education in Denmark were invited to participate in a new
trial. 60 participating schools were stratified based on the share of students of non-Western origin and the average performance on reading tests in 2nd grade in 2013. Within each stratum, schools were randomly allocated to a treatment and a control group.
Experimental Design Details
Randomization Method
Randomization using statistical software (Stata).
Randomization Unit
Schools were the unit of randomization. Within the participating schools, one grade 5 classroom was randomly selected for participation in the trial.
Was the treatment clustered?

Experiment Characteristics

Sample size: planned number of clusters
62 schools
Sample size: planned number of observations
About 1,500 students
Sample size (or number of clusters) by treatment arms
30 schools control, 30 schools treatment
Minimum detectable effect size for main outcomes (accounting for sample design and clustering)

Institutional Review Boards (IRBs)

IRB Name
IRB Approval Date
IRB Approval Number


Post Trial Information

Study Withdrawal

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Is the intervention completed?
Intervention Completion Date
December 13, 2014, 12:00 +00:00
Data Collection Complete
Data Collection Completion Date
Final Sample Size: Number of Clusters (Unit of Randomization)
Was attrition correlated with treatment status?
Final Sample Size: Total Number of Observations
Final Sample Size (or Number of Clusters) by Treatment Arms
Data Publication

Data Publication

Is public data available?

Program Files

Program Files
Reports, Papers & Other Materials

Relevant Paper(s)

Reports & Other Materials