Rounded/square corners - SeaWorld Orlando website

Last registered on December 10, 2025
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Pre-Trial

Trial Information

General Information

Title
Rounded/square corners - SeaWorld Orlando website
RCT ID
AEARCTR-0017385
Initial registration date
December 02, 2025

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
December 08, 2025, 12:42 PM EST

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

Last updated
December 10, 2025, 9:19 PM EST

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

Locations

Country
United States of America
Region

Primary Investigator

Name
Ron Kohavi
Affiliation
Contact Primary Investigator

Other Primary Investigator(s)

PI Name
Ravikiran Rajagopal
PI Affiliation
United Parks & Resorts
Contact Investigator
PI Name
Lukas Vermeer
PI Affiliation
Contact Investigator
PI Name
Jakub Linowski
PI Affiliation
Linowski Interaction Design
Contact Investigator

Additional Trial Information

Status
Completed
Start date
2025-05-19
End date
2025-06-30
Keywords
Behavior, Lab, Other
Additional Keywords
Online, website, user interface
JEL code(s)
C12
Secondary IDs
Prior work
This trial does not extend or rely on any prior RCTs.
Abstract
Do elements with rounded shapes enhance click-through rates?

This is part of the Trustworthy A/B patterns project described at https://bit.ly/trustworthyABPatterns

The first two replications were done with Coop. The OBS trial was approved: https://www.socialscienceregistry.org/trials/17349
The second is at https://www.socialscienceregistry.org/trials/17384
This is the third replication on a US site: SeaWorld Orlando

Consumers frequently encounter digital design elements intended to influence their behavior, from call-to-action buttons to visual cues that guide online decision-making. A recent study published in the Journal of Consumer Research (Biswas et al. 2023) reported that using rounded visual elements increased online click-through rates by 55% in an A/B test—a finding that, if reliable, would have significant implications for marketers, designers, and digital platforms seeking to enhance consumer engagement

We suspect that the paper suffers from the winner's curse and is highly underpowered. See post at https://www.linkedin.com/posts/ronnyk_do-elements-with-rounded-shapes-enhance-click-through-activity-7183554027773734914--ugr/

Paper reference: Curvy Digital Marketing Designs: Virtual Elements with Rounded Shapes Enhance Online Click-Through Rates co-authored by Biswas, Abell, and Chacko (2023)
External Link(s)
Discussion of paper on LinkedIn
The paper: Curvy Digital Marketing Designs: Virtual Elements with Rounded Shapes Enhance Online Click-Through Rates
Trustworthy A/B Testing project page

Registration Citation

Citation
Kohavi, Ron et al. 2025. "Rounded/square corners - SeaWorld Orlando website." AEA RCT Registry. December 10. https://doi.org/10.1257/rct.17385-1.2
Sponsors & Partners
Experimental Details

Interventions

Intervention(s)
SeaWorld had square buttons throughout their website experience, and we were able to programmatically change the buttons to round in the Treatment. This included buttons everywhere, including add-to-cart, the popup asking for email address, and dates buttons.

See https://bit.ly/roundedCornersSeaworldSummary for description with screen shots
Intervention (Hidden)
Intervention Start Date
2025-05-19
Intervention End Date
2025-06-30

Primary Outcomes

Primary Outcomes (end points)
Clickthrough rate
Primary Outcomes (explanation)
Each user who visited the site was assigned 1 if they clicked on any button that was programmatically controlled as round or square, and 0 otherwise (Boolean).
The clickthrough rate is the average over all users of the 0/1/indicator.

Secondary Outcomes

Secondary Outcomes (end points)
Secondary Outcomes (explanation)

Experimental Design

Experimental Design
Users who visited https://seaworld.com/orlando/ were randomized into control/treatment.
They're assigned 1 if they (anytime during the experiment) click on one of the buttons that was programmatically controlled as square or round and zero otherwise.
Experimental Design Details
Randomization Method
Every user who visits the website is randomized into one of the two variants by Optimizely based on a hash of their cookie.
The assignment is consistent for all future visits.
Randomization Unit
User
Was the treatment clustered?
No

Experiment Characteristics

Sample size: planned number of clusters
No clusters
Sample size: planned number of observations
At least 2.4M users for both arms
Sample size (or number of clusters) by treatment arms
1.2M users in each arm
Minimum detectable effect size for main outcomes (accounting for sample design and clustering)
MDE was set to 0.5% on estimated conversion rate of 35%. Using 16*(0.35*0.65)/(0.35*0.005)^2*2 = 2377143 We estimated 4-5 weeks, so agreed to run for 6 weeks to be conservative.
Supporting Documents and Materials

Documents

Document Name
Trustworthy A/B Patterns
Document Type
proposal
Document Description
This is the version of our document published at https://bit.ly/trustworthyABPatterns, as it existed on Google Drive on 5/6/2025, before the experiment started. The key paragraph proposing the replication is:

Rounded/square corners – published result that some believe is highly exaggerated. See https://www.linkedin.com/posts/ronnyk_do-elements-with-rounded-shapes-enhance-cli ck-through-activity-7183554027773734914--ugr Proposed MDE for power calculations on conversion metric: Based on the results of the Coop experiment, we recommend an MDE lower than 0.56%, say 0.5%. This is a tough one to estimate, but several practitioners believe this is much closer to zero than to the 17%+ in the paper.

Relevant experiment by Evidoo: https://www.linkedin.com/posts/jurjenjongejan_ecommerce-abtesting-activity-7275790 931121901568-nXh7
File
Trustworthy A/B Patterns

MD5: ba3e8d9513afe8a81a7735db46757dee

SHA1: b5726c89419d6751cb990cfbaeccaa93cbe2583d

Uploaded At: December 02, 2025

IRB

Institutional Review Boards (IRBs)

IRB Name
IRB Approval Date
IRB Approval Number
Analysis Plan

Post-Trial

Post Trial Information

Study Withdrawal

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Intervention

Is the intervention completed?
Yes
Intervention Completion Date
June 30, 2025, 12:00 +00:00
Data Collection Complete
Yes
Data Collection Completion Date
June 30, 2025, 12:00 +00:00
Final Sample Size: Number of Clusters (Unit of Randomization)
No clustering
Was attrition correlated with treatment status?
No
Final Sample Size: Total Number of Observations
2,896,107
Final Sample Size (or Number of Clusters) by Treatment Arms
1,448,041 in Control 1,448,066 in Treatment
Data Publication

Data Publication

Is public data available?
No

Program Files

Program Files
Yes
Program Files URL
https://bit.ly/roundedCornersComputations
Reports, Papers & Other Materials

Relevant Paper(s)

Reports & Other Materials

Description
Rounded or Square Corners? A Large Replication at SeaWorld® Orlando
Citation
Ronny Kohavi, Jakub Linowski, Lukas Vermeer, and Ravi Rajagopal, 2025. LinkedIn post: https://bit.ly/roundedCornersSeaworldSummary
URL
https://bit.ly/roundedCornersSeaworldSummary