Soon after the introduction of the first Personal Computers the potential benefits associated with their use for exam delivery were quickly realized. Prior to this breakthrough the process of exam delivery and, therefore, the test-taker experience had largely been unchanged for more than 100 years. 

Twenty years ago, virtually all exams were administered via paper and pencil, with many large-scale tests only available to test-takers on one or two days a year. The substantial advance planning and logistical support required for these mass administrations made more frequent testing cost-prohibitive. As a consequence, test-takers often had to rearrange their schedules to accommodate an exam's very limited availability. 

The advent of Computer-Based Testing (CBT) and specially equipped testing labs made more frequent test administrations practical, while preserving the integrity and security of the exam. Today, well over a million exams a month are delivered worldwide via computer and that number continues to grow each year. The individuals taking these tests enjoy a level of convenience and satisfaction unparalleled with paper and pencil testing. 

Simply put, computer-based testing refers to the method by which tests are delivered via a computer, usually at a secure, proctored test center. Unlike paper and pencil exams, which are often monitored by temporary employees hired for the day of testing, computer-based exams are typically proctored by a permanent staff of trained and certified test center administrators. The presence of a professional staff of invigilators is essential to the security of the testing process and ultimately the value and credibility of the exam itself. 

One of the early concerns about the use of computers in the delivery of exams was whether inexperienced computer users would be disadvantaged. Decades of research have shown that test-takers who are administered the same test on computer and on paper perform equally well, even among individuals that have had little or no previous experience in the use of a computer. 

The quality of any exam, whether it's paper or computer-based, is measured against validity, reliability and fairness, in other words, a properly constructed exam must test the appropriate knowledge, skills and abilities, and it must do so consistently for every test-taker and it must avoid any bias that could taint the results. There are scientific approaches to analyze and review exam questions and construction, to ensure they possess the desired difficulty levels. Combine this with the standardized environment offered by computer-based testing and test-takers will be provided with an equal opportunity, a comparable testing experience and a degree of score integrity. 

Computerized exams can look very similar to a traditional paper and pencil test. Multiple choice questions continue to be the most commonly used format for both modes of delivery. Each question typically has four or five answer options from which the correct response(s) must be selected. Instead of using a pencil to fill in a 'bubble' to mark an answer, test-takers use a computer mouse to point to, and click, on the correct response. Just as with a paper-based exam the test-taker can easily see the selection that was made. However, the computer readily allows subsequent changes to an answer without the uncertainty of knowing whether a poorly erased answer might invalidate the new selection. 

In a paper and pencil exam, test-takers must remember items they wish to review prior to the completion of the test. This often results in elaborate notations made in the test booklet or scratch paper, that are meant to indicate which items require further consideration. Time management becomes an essential, but unintended, aspect of the exam. For many exams, the computer environment provides several tools that allow the test-taker to more effectively utilize their allotted time. First, test-takers can electronically 'mark' test questions for review, providing a visual indicator of items that should be revisited. Second, an item review screen allows test-takers to quickly track their progress by viewing a list of all the test questions within the exam, along with an indication as to whether the item has been answered and/or marked for review. Using this review screen, test-takers can select and immediately view any item in the test, thus eliminating the need to flip through the pages of a test booklet in search of a particular question. 

The presentation of items is also enhanced through the use of computer-based testing. Unrestricted by the physical limitations of test booklets, computer administered test questions can be formatted to meet each item's unique requirements. Graphics and reference materials can either be integrated directly into the item or, in the case of very large images, invoked by clicking on an on-screen button. Many tests utilize case studies in which the test-taker reads a passage and then responds to a series of test questions that are associated with that material. Computer delivery makes it possible for the case study contents to appear on one side of the screen and all of its associated test questions to appear on the other, thus allowing test-takers to quickly reference all of the information required. 

In the event of power outage, there are contingency options for ensuring that data is not completely lost and even allow for full recovery. Exams remain resident on the local file server throughout the administration of the test and each time a candidate makes a selection the response is immediately stored on the server when he/she advances to the next item. If there is a blackout, or any other disruption such as a workstation crash, all of the candidate's responses are safely housed on the server's hard drive. When power is restored, or the appointment is transferred from the defective workstation to another computer, the exam can be resumed exactly where the candidate left off, with no loss of time on the exam. Available since the early 1990's, computer-based testing continues to grow in popularity. It is now widely used for admissions testing as well as licensure and certification exams. The adoption rate is expected to continue to grow as test sponsors explore the use of new, innovative item types and advanced multimedia to create ever more engaging and effective assessments. As the technology evolves test-takers will continue to be the beneficiaries of these advancements.