Bring in the Clowns - The Effect of Humor on Health Care

Last registered on June 16, 2023


Trial Information

General Information

Bring in the Clowns - The Effect of Humor on Health Care
Initial registration date
December 23, 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 03, 2023, 5:23 PM EST

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

Last updated
June 16, 2023, 4:35 AM EDT

Last updated is the most recent time when changes to the trial's registration were published.


Primary Investigator

Vienna University of Economics and Business

Other Primary Investigator(s)

PI Affiliation
Vienna University of Economics and Business
PI Affiliation
International Institute for Applied Systems Analysis (IIASA)

Additional Trial Information

Start date
End date
Secondary IDs
Prior work
This trial does not extend or rely on any prior RCTs.
This project evaluates the effect of clown visits in hospitals on the physical and psychological well-being of patients, as assessed by their caregivers, and health care utilization in a middle-income developing country. The authors conduct a field study in cooperation with an international organization for clown visits operating in the Middle East. By randomizing the schedule of standardized interventions in hospitals, short-term hospitalized children are randomly assigned to two groups: clown visit and no clown visit. Field workers approach accompanying caregivers of both groups for consent to participate in the study and their agreement to take part in a telephone interview, held about ten days after recruiting. A comparison of the answers given in the interviews and the accompanying hospital data will shed light on the immediate effects of clown visits and potential spill-over effects on trust in the healthcare system.
External Link(s)

Registration Citation

Grimm, Christine, Melanie Gräser and Roman Hoffmann. 2023. "Bring in the Clowns - The Effect of Humor on Health Care." AEA RCT Registry. June 16.
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Experimental Details


Standardized clown bed-site visits in hospitals as established in the field.
Intervention Start Date
Intervention End Date

Primary Outcomes

Primary Outcomes (end points)
Our outcome variables are
A) answers in the telephone interview with caregivers and
B) hospital data
to learn about
a) recovery of the patient
b) perception of the hospital stay and
c) perception of the public health care system

Update June 2023:
Despite initial approval from the Ministry of Health, project partner and hospital, access to the administrative data from the hospital was ultimately denied due to legal reasons at the end of the data collection. Our analysis has to adapt accordingly.
Primary Outcomes (explanation)
Recovery of the patient: length of stay, number of complications, ratings of autonomy and recovery of the patient
Perception of the hospital stay: ratings of mood, appetite, comfortability
Perception of the public health care system: return rate for follow-up visits, ratings on perception of hospital (/staff) and health care system ( in comparison to the private system).

Secondary Outcomes

Secondary Outcomes (end points)
Secondary Outcomes (explanation)

Experimental Design

Experimental Design
Clowns visit hospitals on a randomized schedule. At one (two) out of seven days, there will be a clown visit. At six (five) out of seven days, there will be no clown visit. Naturally, some children will see a clown and others do not.
Data collectors independently approach caregivers of both groups for consent to participate in the study. Participants are contacted for a telephone interview and data on the patient is collected from the hospital.
Experimental Design Details
For our project, we randomize the days of weekly clown visits in hospitals. Clown visits were already implemented in all participating hospitals before our project and happened once (or twice) a week. While we randomize the day of the visit, we keep the frequency of the visits for ethical reasons.
The main target group of our study is young patients with an average length of stay between 2 and 5 days. Dependent on their entry and release date, patients naturally select into two groups. One group whose stays will overlap with a clown visit and another group whose stays will not overlap with a clown visit. By randomizing the day of the visit we can also separate the days with a clown visit from the days without a clown visit in each hospital.
Data collectors independently visit the hospitals to recruit participants and collect consent forms. Participants agree to be contacted around ten days after the recruitment for a telephone interview and for data collectors to collect additional data on the patient from the hospital.
Randomization Method
The randomization was done with the computer using stata.
The randomization can be replicated with the "generate random_number" command for the hospitals in each week. The random number is assigned to seven groups of equal size representing the weekdays. The starting seed is 1234. For every week an additional 10 is added to the seed.
Hospitals that entered our sample group after the start date (including those with two visits) follow an individual do-file that is set up in the same way, using a different starting seed.
Randomization Unit
Day of clown visit per week and hospital.
Was the treatment clustered?

Experiment Characteristics

Sample size: planned number of clusters
We plan to have a threefold analysis. A) treats every patient/caregiver as one observation, B) controls for the day of arrival and hospitals to account for spill-over effects, C) treats the daily situation at each hospital as one observation.
A) 2000 patients / caregivers
B) 375 days of arrival and hospital (5 hospitals x 15 days/month(rough estimate) x 5 months) (in case of adjustments: additional hospitals, fewer days per month covered)
C) 5 hospitals ( in case of adjustments: additional hospitals)
Sample size: planned number of observations
A) 2000 patients / caregivers B) 2000 patients / caregivers C) 500 days (5 hospitals x 20 days/month(rough estimate) x 5 months)
Sample size (or number of clusters) by treatment arms
A)1000 patients / caregivers control + 1000 patients / caregivers treatment
B)1000 patients / caregivers control + 1000 patients / caregivers treatment
C) 428 days and hospital control + 71 days and hospital treatment
Minimum detectable effect size for main outcomes (accounting for sample design and clustering)
A) Nb of sites: 5, N= 2000, a=0.05, P=0.80, MDES=0.13 B) Nb of sites: 5, Nb of "cluster"= 75(15x5), N=2000, a=0.05, P=0.80, MDES=0.14 C) Nb of sites:5, N=500, a=0.05, P=0.80, p=1/7, MDES= 0.25

Institutional Review Boards (IRBs)

IRB Name
WU Ethics Board
IRB Approval Date
IRB Approval Number
IRB Name
Ministry of Health, Palestine
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