Diagnosing Quality: Learning, Amenities, and the Demand for Health Care

Last registered on July 16, 2020


Trial Information

General Information

Diagnosing Quality: Learning, Amenities, and the Demand for Health Care
Initial registration date
July 15, 2020
Last updated
July 16, 2020, 3:32 PM EDT



Primary Investigator


Other Primary Investigator(s)

PI Affiliation
PI Affiliation
University of Michigan, Ann Arbor
PI Affiliation
University of Michigan, Ann Arbor

Additional Trial Information

Start date
End date
Secondary IDs
We partnered with a cataract surgery clinic serving mostly low-income elderly patients in Mexico City to evaluate a randomized price experiment to study how take-up of cataract surgery may be influenced by the provision of amenities in early stages of the patient-provider interaction. The clinic with which we partnered for the experiment offers substantial benefits over the public sector (care meeting international standards and substantially reduced wait times), and is relatively attractive to patients seeking care in the private market because the price of the most basic surgery is set well below competitors’ prices. While consultations represent a large fraction of physicians’ time, surgeries represent a considerably larger fraction of the clinic’s profits. When we were first approached by the clinic, they were particularly interested in maximizing surgery take-up among patients with a positive diagnosis of cataracts. The monetary price of the basic consultation was 50 pesos (roughly 4 USD), and patients had the option to pay a fee to reduce the time spent in the waiting room before being seen by the physician. Clinic management was under the impression that patients that paid the fee to reduce waiting during the first consultation were significantly more likely to take-up the surgery, and believed this pattern may be attributable to the fact that these patients’ first interaction with the clinic was (relatively) pleasant. Accordingly, clinic management decided to experiment with the price of the premium consultation to see if greater take-up could be achieved. The experiment would consist of offering the premium consultation at randomized, promotional prices, subject to some constraints.

External Link(s)

Registration Citation

Adhvaryu, Achyuta et al. 2020. "Diagnosing Quality: Learning, Amenities, and the Demand for Health Care." AEA RCT Registry. July 16. https://doi.org/10.1257/rct.6156-1.0
Experimental Details


Intervention Start Date
Intervention End Date

Primary Outcomes

Primary Outcomes (end points)
Demand for Premium Consultation and Surgery take-up
Primary Outcomes (explanation)

Secondary Outcomes

Secondary Outcomes (end points)
Secondary Outcomes (explanation)

Experimental Design

Experimental Design
The experiment took place from January to April 2013. During this period, each patient that arrived for a diagnostic consultation was enrolled in the study. The receptionist who greeted patients explained the variety of consultations available. There were three types of diagnostic consultation available to patients:

• Basic (50 pesos): standard wait time, diagnosis in a standard room, no amenities
• Reduced wait time (200 pesos): reduced wait time, diagnosis in a standard room, no amenities
• Premium (randomized price – 250, 300, or 350): reduced wait time, upgraded room, additional

Once the options were made known, the receptionist handed a promotion card in a closed envelope to each patient from a previously randomly ordered stack. The ticket reported the randomized price of the premium consultation cost (250, 300 or 350 pesos). The patient was told that she was able to access the premium consultation at the price assigned by the ticket, and was also told the approximate wait time. The average daily number of patients was about 80, with a maximum daily number over the experimental period of roughly 150. The average expected wait time was about 3.5 hours.

Registration at the reception desk took place in a relatively private environment, as all previous patients in line were already sitting in one of the waiting rooms and patients waited in line outside the clinic before approaching the reception desk one by one. Unsurprisingly, no patient complained that the promotional price offered to them was higher than that offered to others.

Patients paying for the premium consultation were sent directly to the premium facility across the street for their consultation after registration at the reception desk. In the premium consultation building, patients were seen in a more comfortable consultation room, but the procedure for cataract detection was exactly the same as the one performed in the regular clinic. If diagnosed with cataracts, patients were then sent to see a “counselor,” a person different from the diagnostician who gave them the diagnosis, who explained options for surgery and prices and gave the opportunity to schedule surgery at the clinic. All diagnosed patients, irrespective of type of consultation, were seen by the same counselor.

Counselors were not informed if patients paid for the premium consultation, and followed the same protocol for providing information about available surgery options to all patients.
Experimental Design Details
Randomization Method
The receptionist handed a promotion card in a closed envelope to each patient from a previously randomly ordered stack. The cards were printed 8 to a page. Given the above-mentioned constraints imposed by clinic management, on each page, 3 cards had a promotional price of 250 pesos, 3 had a price of 300, and 2 had a promotional price of 350. The printing firm then took care of shuffling, numbering and stacking the cards with different promotional prices, which were given to the reception desk at the clinic during the experiment.
Randomization Unit
Was the treatment clustered?

Experiment Characteristics

Sample size: planned number of clusters
2085 Patients
Sample size: planned number of observations
2085 Patients
Sample size (or number of clusters) by treatment arms
782 patients Price 250 (Pesos)
747 patients Price 300 (Pesos)
556 patients Price 350 (Pesos)
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?
Data Collection Complete
Data Publication

Data Publication

Is public data available?

Program Files

Program Files
Reports, Papers & Other Materials

Relevant Paper(s)

Reports & Other Materials