Misplaced Pages

#827172

42-641: The Oxford Placement Test ( OPT ), also called the Oxford Online Placement Test ( OOPT ), is an on demand computer-adaptive test of the English language for non-native speakers of English, reporting at Pre-A1, A1, A2, B1, B2, C1, and C2 levels of the Common European Framework of Reference (CEFR). The test was developed by Oxford University Press (OUP) to provide institutions with a quick, reliable way to place English language students into

84-450: A Bayesian method may have to be used temporarily. The CAT algorithm is designed to repeatedly administer items and update the estimate of examinee ability. This will continue until the item pool is exhausted unless a termination criterion is incorporated into the CAT. Often, the test is terminated when the examinee's standard error of measurement falls below a certain user-specified value, hence

126-402: A CAT (the following is adapted from Weiss & Kingsbury, 1984 ). This list does not include practical issues, such as item pretesting or live field release. A pool of items must be available for the CAT to choose from. Such items can be created in the traditional way (i.e., manually) or through automatic item generation . The pool must be calibrated with a psychometric model, which is used as

168-522: A CD-ROM test provided in partnership with Cambridge English. The success of the Oxford Placement Test led to the design of the Oxford Test of English , and online computer-adaptive English Proficiency test, used as proof of English ability for university entry and employment. The Oxford Placement Test is designed to provide a quick, accurate measurement of a test taker's English language ability on

210-455: A CEFR band (Pre-A1 to C2) and as a standardized score (0-120) on the OPT scale. Report cards provide a breakdown by section, including the time taken to complete each section. Report cards can carry the institution's branding. The CEFR levels and standardized scores are shown in this table: Computer-adaptive test CAT successively selects questions for the purpose of maximizing the precision of

252-450: A basis for the remaining four components. Typically, item response theory is employed as the psychometric model. One reason item response theory is popular is because it places persons and items on the same metric (denoted by the Greek letter theta), which is helpful for issues in item selection (see below). In CAT, items are selected based on the examinee's performance up to a given point in

294-426: A fixed set of items administered to all examinees, computer-adaptive tests require fewer test items to arrive at equally accurate scores. The basic computer-adaptive testing method is an iterative algorithm with the following steps: Nothing is known about the examinee prior to the administration of the first item, so the algorithm is generally started by selecting an item of medium, or medium-easy, difficulty as

336-536: A given item ). Given a set of items, a multidimensional computer adaptive test (MCAT) selects those items from the bank according to the estimated abilities of the student, resulting in an individualized test. MCATs seek to maximize the test's accuracy, based on multiple simultaneous examination abilities (unlike a computer adaptive test – CAT – which evaluates a single ability) using the sequence of items previously answered (Piton-Gonçalves & Aluisio, 2012). Computer adaptive sequential testing From Misplaced Pages,

378-410: A large bank of questions, based on the test taker's response to the previous question. This makes for a better test experience for test takers than traditional language tests. The OPT's online Learning Management System (LMS) allows institutions to administer the test at physical institutions, or for the test to be taken at the test taker's home. Results are available immediately and are reported as

420-438: A large enough sample to obtain stable item statistics. This sample may be required to be as large as 1,000 examinees. Each program must decide what percentage of the test can reasonably be composed of unscored pilot test items. Although adaptive tests have exposure control algorithms to prevent overuse of a few items, the exposure conditioned upon ability is often not controlled and can easily become close to 1. That is, it

462-427: A new item is to be selected instantaneously. Psychometricians experienced with IRT calibrations and CAT simulation research are necessary to provide validity documentation. Finally, a software system capable of true IRT-based CAT must be available. In a CAT with a time limit it is impossible for the examinee to accurately budget the time they can spend on each test item and to determine if they are on pace to complete

SECTION 10

#1732837217828

504-411: A priori distribution of examinee ability, and has two commonly used estimators: expectation a posteriori and maximum a posteriori . Maximum likelihood is equivalent to a Bayes maximum a posteriori estimate if a uniform ( f (x)=1) prior is assumed. Maximum likelihood is asymptotically unbiased, but cannot provide a theta estimate for an unmixed (all correct or incorrect) response vector, in which case

546-440: A sizable sample and then analyzed. To achieve this, new items must be mixed into the operational items of an exam (the responses are recorded but do not contribute to the test-takers' scores), called "pilot testing", "pre-testing", or "seeding". This presents logistical, ethical , and security issues. For example, it is impossible to field an operational adaptive test with brand-new, unseen items; all items must be pretested with

588-557: A timed test section. Test takers may thus be penalized for spending too much time on a difficult question which is presented early in a section and then failing to complete enough questions to accurately gauge their proficiency in areas which are left untested when time expires. While untimed CATs are excellent tools for formative assessments which guide subsequent instruction, timed CATs are unsuitable for high-stakes summative assessments used to measure aptitude for jobs and educational programs. There are five technical components in building

630-500: A verbal exam may need to be composed of equal numbers of analogies, fill-in-the-blank and synonym item types. CATs typically have some form of item exposure constraints, to prevent the most informative items from being over-exposed. Also, on some tests, an attempt is made to balance surface characteristics of the items such as gender of the people in the items or the ethnicities implied by their names. Thus CAT exams are frequently constrained in which items it may choose and for some exams

672-513: Is item response theory (IRT). IRT is also the preferred methodology for selecting optimal items which are typically selected on the basis of information rather than difficulty, per se. A related methodology called multistage testing (MST) or CAST is used in the Uniform Certified Public Accountant Examination . MST avoids or reduces some of the disadvantages of CAT as described below. CAT has existed since

714-458: Is administered, the CAT updates its estimate of the examinee's ability level. If the examinee answered the item correctly, the CAT will likely estimate their ability to be somewhat higher, and vice versa. This is done by using the item response function from item response theory to obtain a likelihood function of the examinee's ability. Two methods for this are called maximum likelihood estimation and Bayesian estimation . The latter assumes an

756-645: Is common for some items to become very common on tests for people of the same ability. This is a serious security concern because groups sharing items may well have a similar functional ability level. In fact, a completely randomized exam is the most secure (but also least efficient). Review of past items is generally disallowed. Adaptive tests tend to administer easier items after a person answers incorrectly. Supposedly, an astute test-taker could use such clues to detect incorrect answers and correct them. Or, test-takers could be coached to deliberately pick wrong answers, leading to an increasingly easier test. After tricking

798-450: Is extremely important. Some modifications are necessary for a pass/fail CAT, also known as a computerized classification test (CCT) . For examinees with true scores very close to the passing score, computerized classification tests will result in long tests while those with true scores far above or below the passing score will have shortest exams. For example, a new termination criterion and scoring algorithm must be applied that classifies

840-430: The 1970s, and there are now many assessments that utilize it. Additionally, a list of active CAT exams is found at International Association for Computerized Adaptive Testing, along with a list of current CAT research programs and a near-inclusive bibliography of all published CAT research. Adaptive tests can provide uniformly precise scores for most test-takers. In contrast, standard fixed tests almost always provide

882-787: The CEFR scale. The test consists of two sections: Language Use and Listening. Within the Use of English Section, in addition to standard grammar, lexis and listening questions, the test design focuses on meaning beyond the sentence, including implied meaning; the language sampled in the test is an accurate predictor of general language ability. The test has been independently reviewed and found perform better than other placement tests. The Oxford Placement Test uses computer-adaptive testing (CAT) technology. Computer adaptive tests can be more efficient and provide more precise measurement than traditional tests. The adaptive test works by selecting each successive question from

SECTION 20

#1732837217828

924-448: The adaptive test into building a maximally easy exam, they could then review the items and answer them correctly—possibly achieving a very high score. Test-takers frequently complain about the inability to review. Because of the sophistication, the development of a CAT has a number of prerequisites. The large sample sizes (typically hundreds of examinees) required by IRT calibrations must be present. Items must be scorable in real time if

966-417: The best precision for test-takers of medium ability and increasingly poorer precision for test-takers with more extreme test scores. An adaptive test can typically be shortened by 50% and still maintain a higher level of precision than a fixed version. This translates into time savings for the test-taker. Test-takers do not waste their time attempting items that are too hard or trivially easy. Additionally,

1008-409: The common "mastery test" where the two classifications are "pass" and "fail", but also includes situations where there are three or more classifications, such as "Insufficient", "Basic", and "Advanced" levels of knowledge or competency. The kind of "item-level adaptive" CAT described in this article is most appropriate for tests that are not "pass/fail" or for pass/fail tests where providing good feedback

1050-437: The confidence interval approach because it minimizes the conditional standard error of measurement, which decreases the width of the confidence interval needed to make a classification. ETS researcher Martha Stocking has quipped that most adaptive tests are actually barely adaptive tests (BATs) because, in practice, many constraints are imposed upon item choice. For example, CAT exams must usually meet content specifications;

1092-411: The constraints may be substantial and require complex search strategies (e.g., linear programming ) to find suitable items. A simple method for controlling item exposure is the "randomesque" or strata method. Rather than selecting the most informative item at each point in the test, the algorithm randomly selects the next item from the next five or ten most informative items. This can be used throughout

1134-410: The correct level English class. Placement testing is a key stage in the learning cycle. The Oxford Placement Test, the first globally available online computer-adaptive placement test, was launched in 2009 and has placed millions of test takers since it was launched. It tests British English, American English, or a mix of the two language variants. The OPT replaced the now retired Quick Placement Test,

1176-455: The cutscore to be administered every item in the bank without the algorithm making a decision. The item selection algorithm utilized depends on the termination criterion. Maximizing information at the cutscore is more appropriate for the SPRT because it maximizes the difference in the probabilities used in the likelihood ratio . Maximizing information at the ability estimate is more appropriate for

1218-406: The cutscore. Note that this is a point hypothesis formulation rather than a composite hypothesis formulation that is more conceptually appropriate. A composite hypothesis formulation would be that the examinee's ability is in the region above the cutscore or the region below the cutscore. A confidence interval approach is also used, where after each item is administered, the algorithm determines

1260-474: The exam based on what is known about the examinee from previous questions. From the examinee's perspective, the difficulty of the exam seems to tailor itself to their level of ability. For example, if an examinee performs well on an item of intermediate difficulty, they will then be presented with a more difficult question. Or, if they performed poorly, they would be presented with a simpler question. Compared to static tests that nearly everyone has experienced, with

1302-415: The examinee into a category rather than providing a point estimate of ability. There are two primary methodologies available for this. The more prominent of the two is the sequential probability ratio test (SPRT). This formulates the examinee classification problem as a hypothesis test that the examinee's ability is equal to either some specified point above the cutscore or another specified point below

Oxford Placement Test - Misplaced Pages Continue

1344-435: The first item. As a result of adaptive administration, different examinees receive quite different tests. Although examinees are typically administered different tests, their ability scores are comparable to one another (i.e., as if they had received the same test, as is common in tests designed using classical test theory). The psychometric technology that allows equitable scores to be computed across different sets of items

1386-438: The 💕 (Redirected from Computer adaptive sequential testing ) Computer-adaptive sequential testing ( CAST ) is another term for multistage testing . A CAST test is a type of computer-adaptive test or computerized classification test that uses pre-defined groups of items called testlets rather than operating at the level of individual items. CAST is a term introduced by psychometricians working for

1428-401: The past 10 years. Once not accepted in medical facilities and laboratories, CAT testing is now encouraged in the scope of diagnostics. Like any computer-based test , adaptive tests may show results immediately after testing. Adaptive testing, depending on the item selection algorithm , may reduce exposure of some items because examinees typically receive different sets of items rather than

1470-428: The probability that the examinee's true-score is above or below the passing score. For example, the algorithm may continue until the 95% confidence interval for the true score no longer contains the passing score. At that point, no further items are needed because the pass-fail decision is already 95% accurate, assuming that the psychometric models underlying the adaptive testing fit the examinee and test. This approach

1512-412: The same metric. Therefore, if the CAT has an estimate of examinee ability, it is able to select an item that is most appropriate for that estimate. Technically, this is done by selecting the item with the greatest information at that point. Information is a function of the discrimination parameter of the item, as well as the conditional variance and pseudo-guessing parameter (if used). After an item

1554-489: The statement above that an advantage is that examinee scores will be uniformly precise or "equiprecise." Other termination criteria exist for different purposes of the test, such as if the test is designed only to determine if the examinee should "Pass" or "Fail" the test, rather than obtaining a precise estimate of their ability. In many situations, the purpose of the test is to classify examinees into two or more mutually exclusive and exhaustive categories. This includes

1596-697: The test, or only at the beginning. Another method is the Sympson-Hetter method, in which a random number is drawn from U(0,1), and compared to a k i parameter determined for each item by the test user. If the random number is greater than k i , the next most informative item is considered. Wim van der Linden and colleagues have advanced an alternative approach called shadow testing which involves creating entire shadow tests as part of selecting items. Selecting items from shadow tests helps adaptive tests meet selection criteria by focusing on globally optimal choices (as opposed to choices that are optimal for

1638-493: The test. However, the CAT is obviously not able to make any specific estimate of examinee ability when no items have been administered. So some other initial estimate of examinee ability is necessary. If some previous information regarding the examinee is known, it can be used, but often the CAT just assumes that the examinee is of average ability – hence the first item often being of medium difficulty level. As mentioned previously, item response theory places examinees and items on

1680-556: The testing organization benefits from the time savings; the cost of examinee seat time is substantially reduced. However, because the development of a CAT involves much more expense than a standard fixed-form test, a large population is necessary for a CAT testing program to be financially fruitful. Large target populations can generally be exhibited in scientific and research-based fields. CAT testing in these aspects may be used to catch early onset of disabilities or diseases. The growth of CAT testing in these fields has increased greatly in

1722-414: The whole population being administered a single set. However, it may increase the exposure of others (namely the medium or medium/easy items presented to most examinees at the beginning of the test). The first issue encountered in CAT is the calibration of the item pool. In order to model the characteristics of the items (e.g., to pick the optimal item), all the items of the test must be pre-administered to

Oxford Placement Test - Misplaced Pages Continue

1764-438: Was originally called "adaptive mastery testing" but it can be applied to non-adaptive item selection and classification situations of two or more cutscores (the typical mastery test has a single cutscore). As a practical matter, the algorithm is generally programmed to have a minimum and a maximum test length (or a minimum and maximum administration time). Otherwise, it would be possible for an examinee with ability very close to

#827172