Enables scalable, fair exam delivery with up to 10× greater optimization complexity
Prometric, a global leader in assessment services, delivers certification and licensure exams worldwide. To support its Linear On-the-Fly Testing (LOFT) model, where every candidate receives a unique exam. Prometric needed a high-performance optimization engine capable of handling complex constraints while ensuring fairness, speed, and scalability.
Business challenge
To deliver fair, high-stakes certification exams at scale, Prometric must ensure that every candidate receives a test that is statistically equivalent in difficulty, despite each exam being uniquely generated. With thousands of constraints spanning subject domains, difficulty levels, and content exposure, the process of assembling exams becomes highly complex.
As client demands grew and exam models became more sophisticated, legacy optimization tools struggled to keep up, leading to performance limitations and inconsistent results. How could Prometric generate accurate, balanced exams in real time while handling increasing complexity?
Transformation
To overcome the limitations of its legacy approach, Prometric implemented IBM ILOG CPLEX Optimization Studio to power its exam assembly process. By using mathematical optimization, Prometric can model each exam as a complex decision problem, where every question is selected based on strict constraints and statistical requirements.
CPLEX enables the system to evaluate thousands of variables simultaneously, ensuring that each generated exam meets all domain, difficulty, and fairness criteria while optimizing for balanced item exposure across the question bank. The solution integrates seamlessly with Prometric’s proprietary platforms, allowing exams to be generated in real time or ahead of scheduled test sessions.
With CPLEX, Prometric transformed its ability to handle increasing complexity, delivering faster, more accurate, and scalable exam generation without compromising quality.
Results
Handles
complex exam models with up to 10× more constraints, enabling more sophisticated and scalable test design
Accelerates
exam generation in real time, reducing wait times and improving the candidate experience
Improves
statistical accuracy with tighter tolerances, ensuring fair and consistent exams for every candidate
Business challenge story
Overcoming optimization limits to deliver fair, high-stakes exams at scale
From professional certifications to high-stakes licensure exams, organizations rely on Prometric to assess candidates accurately and fairly. To support its Linear On-the-Fly Testing (LOFT) model, Prometric dynamically generates a unique exam for each candidate from large item banks.
This approach creates a complex optimization problem. Each exam must satisfy thousands of constraints—covering subject domains, difficulty levels, statistical properties, and content exposure—while ensuring every candidate receives an equivalent and fair test.
As client requirements evolved, the number and complexity of these constraints increased significantly. Prometric’s existing optimization tools began to struggle, leading to slower performance and inconsistent results when handling more advanced exam models.
“We’re solving a highly complex optimization problem every time we generate an exam. As the number of constraints increased, we needed a solution that could handle that complexity reliably and at speed.”
David Dixon,
Director at Prometric
Transformation story
Powering exam optimization with advanced decision analytics
To overcome the limitations of its previous approach, Prometric turned to IBM ILOG CPLEX Optimization Studio to modernize its exam assembly process. By adopting a mathematical optimization framework, Prometric transformed exam generation into a scalable decision optimization problem—capable of handling thousands of constraints simultaneously.
Working with IBM Business Partner Cresco International, Prometric implemented CPLEX within its existing architecture, enabling seamless integration with its proprietary item banking and test delivery systems. This allowed the organization to dynamically generate exams that meet strict domain, difficulty, and statistical requirements, while optimizing for balanced question exposure across large item banks.
With CPLEX, Prometric gained the ability to process significantly more complex models with greater speed and reliability. Exams can now be generated in real time or pre-scheduled for delivery, ensuring both operational efficiency and a smooth candidate experience.
David Dixon adds:
“By moving to CPLEX, we were able to handle a much higher level of complexity while improving performance. It gave us the confidence that our optimization models would consistently deliver accurate and reliable results.”
Results story
Driving faster, more accurate exam delivery at scale
With IBM ILOG CPLEX Optimization Studio in place, Prometric has significantly enhanced its ability to generate fair, high-quality exams at scale—transforming how it delivers assessments to clients worldwide.
By leveraging advanced optimization, Prometric can now handle far more complex constraint models while maintaining speed and reliability. Exams are generated faster, allowing candidates to begin testing with minimal delay, while improved statistical precision ensures greater consistency and fairness across all test variations.
David Dixon notes:
“With CPLEX, we’re able to solve much more complex models than before, and do it reliably. That means we can generate exams faster while maintaining the accuracy and fairness our clients expect.”
These improvements have strengthened both operational efficiency and the candidate experience. By reducing processing time and increasing confidence in exam equivalence, Prometric can support growing client demands while upholding the integrity of high-stakes assessments.
Prometric
Prometric is a global leader in assessment services, delivering certification and licensure exams across a wide range of industries. Headquartered in Baltimore, Maryland, Prometric supports clients worldwide through a network of secure test centers and online testing solutions.
The company provides end-to-end assessment services, including test development, item banking, psychometric analysis, and exam delivery. Prometric serves professional organizations, academic institutions, and government bodies, helping them design and administer high-stakes exams that meet rigorous standards for fairness, accuracy, and security.
About Cresco International
Cresco International, headquartered in Dallas, TX, provides business management, resources and data technology to organizations. Its offerings include: IBM Business Analytics software, marketing analytics tools, cloud solutions, consulting services, and technology support and training.
