General practitioners’ claiming of fees: An experimental study on the effect of feedback

Last registered on May 21, 2024


Trial Information

General Information

General practitioners’ claiming of fees: An experimental study on the effect of feedback
Initial registration date
May 14, 2024

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
May 21, 2024, 10:45 AM EDT

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


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Primary Investigator

Norwegian Institute of Public Health

Other Primary Investigator(s)

PI Affiliation
Norwegian Health Economics Administration
PI Affiliation
Institute of Health and Society, University of Oslo

Additional Trial Information

On going
Start date
End date
Secondary IDs
Prior work
This trial does not extend or rely on any prior RCTs.
Each year, Norway disburses reimbursements totaling around 665 millions dollar to its general practitioners (GPs). The system operates on a fee-for-service basis, predominately relying on trust. Under this system, GPs receive compensation determined by their fee utilization which ideally reflects their volume of health services. However, there is considerable variability in fee utilization, leading to diverse amounts of reimbursement being issued to GPs.

This study aims to investigate the extent to which GPs respond to information indicating that they are among the GPs receiving the highest reimbursements from HELFO. More specifically, we randomly assign municipalities into a treatment group and a comparison group, with approximately equal numbers of GPs in each group.

It is expected that the results of this study will serve as a resourceful guidance for policymakers, to how responsive GPs are to information on their reimbursement claims compared to others in a cost-efficient channel. In addition, it will provide a reference regarding which GPs are the most responsive.
External Link(s)

Registration Citation

Grøsland, Mari, Jens-Christian Haatvedt and Bjørn-Atle Reme . 2024. "General practitioners’ claiming of fees: An experimental study on the effect of feedback ." AEA RCT Registry. May 21.
Experimental Details


Intervention Start Date
Intervention End Date

Primary Outcomes

Primary Outcomes (end points)
Amount of reimbursement paid out to GPs, Number of support calls to HELFO
Primary Outcomes (explanation)
Amount of reimbursement paid out for specific fees.

Secondary Outcomes

Secondary Outcomes (end points)
Secondary Outcomes (explanation)

Experimental Design

Experimental Design
We randomize GPs to the treatment and comparison group based on the municipality (district in Oslo, Bergen, Trondheim, and Stavanger) where they work. To enhance statistical power, we implemented a blocked experiment pairing neighboring municipalities. Within each pair one municipality (district) will be randomized to treatment (letter with notification) and comparison (letter without notification). This blocking strategy ensures that the treatment is not randomly concentrated in specific areas of the country, mitigating potential challenges during the analysis phase.
Experimental Design Details
Not available
Randomization Method
Randomization is done in office by a computer
Randomization Unit
Practice municipality/district
Was the treatment clustered?

Experiment Characteristics

Sample size: planned number of clusters
Sample size: planned number of observations
Sample size (or number of clusters) by treatment arms
195 municipalities/districts in control, 196 municipalities/districts in 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