Reliability Of Such Tests Research Articles

Experimental study on the sound transmission loss suite at the University of Technology Sydney

Sound transmission loss suites are essential testing facilities for measuring the sound insulation properties of building elements and assessing noise attenuation. However, inconsistencies in test results can arise due to variations in the size, shape, and construction of test rooms across different laboratories, with biases introduced by the room acoustics or acoustical environment of the facility itself. To evaluate the reliability of such testing, we conducted an experimental study on the sound transmission loss suite at the University of Technology Sydney. Our investigation focused on three key factors: estimating the maximum achievable sound reduction using a heavyweight wall installed at the test aperture on the source room side, testing the effectiveness of vibration isolation between reverberation rooms, and assessing the decoupling of the sound field within the reverberation rooms.

Simple hearing test utilizing a soundproofing headphone with acoustic filters

Hearing loss is a significant quality-of-life (QOL) issue in aging populations and is linked to social isolation, dementia, and depression. Early detection and treatment of hearing loss are critically important aspects of preventing cognitive decline and dementia. To date, smartphone, or tablet-based hearing test methods have been proposed to increase the rate of hearing loss detection outside of the hospital. However, simple hearing tests may be performed without adequate soundproofing facilities; therefore, the reliability of such tests in noisy environments is questionable. In this study, we propose a simple hearing test method that uses a soundproof active noise control (ANC) headphone with acoustic-filtering earcups. The ANC headphones provide sufficient soundproofing over a wide frequency range, and the acoustic-filtering earcups provide effective soundproofing around the test frequency. The proposed earcup is equipped with a Helmholtz resonator (HR) array, wherein multiple HRs are densely arrayed in a honeycomb structure. The muffling effect of the HRs effectively attenuated the noise at a specific frequency. This property is useful for high-accuracy hearing tests, in which the noise around the test frequency is sufficiently reduced. The prototype device attained a maximum noise attenuation of 50 dB at approximately 4 kHz and provided hearing tests that were as accurate as those obtained in a soundproof room.

Comparison of three methods for detection of anti-SARS-CoV-2 antibodies

A novel positive-sense RNA virus named Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) was identified in December 2019 in China. It is a systemic disease that includes severe respiratory distress, coronavirus disease 19 (Covid-19). The primary way of transmitting this virus is person-to-person contact via respiratory droplets, but it can also be transmitted by contaminated surfaces. Symptoms range from mild to severe, and the virus spreads quickly. On 11 March 2020 Covid-19 was declared a pandemic by the World Health Organization. The standard way to identify the presence of the virus is to detect its genome using real-time reverse transcriptase polymerase chain reaction (RT-PCR). It can be applied to respiratory tract samples such as nasopharyngeal swabs, sputum and bronchoalveolar lavage. In order to identify contact with the virus and immunological response of the individual, tests based on immunoassays were developed. Many of those tests were produced in short periods of time and they mostly differ on the sample that can be used (serum, plasma or whole blood), complexity and/or expense, and the class of the antibody they detect. The reliability of such tests is of high importance for epidemiological surveys as well as for the development of a vaccine. The aim of this study was to compare three commercially available immunoassay tests. Our results show that different serological tests have different sensitivity and specificity, and that the rapid option, which is the easiest to perform and has the lowest cost, provides the least reliable results.

Experiments with Stand-Alone Sand-Screen Specimens for Thermal Projects

Summary Most of the test protocols developed to evaluate sand-screen designs were based on scaled-screen test coupons. There have been discussions regarding the reliability of such tests on scaled test coupons. This paper presents the results of tests on wire-wrapped screen (WWS) and slotted liner (SL) test coupons for typical onshore Canada McMurray formation sand. A unique sand control evaluation apparatus has been designed and built to accommodate all common stand-alone screens that are 3.5 in. in diameter and 12 in. in height. This setup provides the capability to have a radial measurement of pressure across the sandpack and screen for three-phase flow. Certain challenges during testing such as establishing uniform radial flow and measuring the differential pressure are outlined. Produced sand is also measured during the test. The main outputs of the test are to assess the sand control performance and the mode of sanding in different flow directions, flow rates, and flow regimes. It was possible to establish uniform radial flow in both high- and low-permeability sandpacks. However, the establishment of radial flow in sandpacks with very high permeability was challenging. The pressure measurement at different points in the radial direction around the screen indicated a uniform radial flow. Results of the tests on a representative particle size distribution (PSD) from the McMurray Formation on the WWS and SL test coupons with commonly used specifications in the industry (aperture sizes of 0.012, 0.014, and 0.016 in. for WWS and 0.012, 0.016, 0.018, and 0.020 in. for SL) have shown similar sanding and flow performances. We also included aperture sizes smaller and larger than the common practice. Similar to previous tests, narrower apertures are proven to be less resistant to plugging than wider slots for both WWS and SL. Accumulation of fines close to the screen causes significant pore plugging when conservative aperture sizes were used for both WWS and SL. In contrast, using the test coupon with a larger aperture size than the industry practice resulted in excessive sanding. The experiments under linear flow seem more conservative because their results show more produced sand and smaller retained permeability in comparison to the testing under radial flow. This work discusses the significance, procedure, challenges, and early results of physical modeling of stand-alone screens in thermal operation. It also provides insight into the fluid flow, fines migration, clogging, and bridging in the vicinity of sand screens.

The quality of measurement properties of neurocognitive assessment in brain tumor clinical trials over the last 30 years: a COSMIN checklist-based approach.

To provide an exhaustive review of the neuropsychological examination as conducted in brain tumor clinical trials over the last 30 years and to provide objective ratings about the reliability and suitability of such tests in neurooncological research and clinical practice. Methodologies and tools provided by the COnsensus-based Standards for the selection of health Measurement INstruments (COSMIN) were exploited in order to assess the measurement properties of questionnaires and performance-based instruments used to evaluate cognitive functioning in brain tumor clinical trials from 1997 to 2017. Twenty-six brain tumor clinical trials were analyzed and an overall set of 10 neuropsychological tests was identified. A list of 24 studies concerning the reliability of such tests was analyzed. Reliability and level of evidence scores for each study and for each test were obtained. The results revealed relevant faults about the quality of measurements and the suitability of the neurocognitive assessment batteries most commonly used in brain tumor clinical trials. Our findings suggest that the cognitive assessment in brain tumor clinical trials should be implemented according to specific endpoints and should be addressed to investigate all the cognitive domains known to be affected by brain tumor and treatment.

Insights into toxicology, safety pharmacology, and drug dependence testing: The performance and predictive values of nonclinical tests

The pre-marketing testing of drugs and chemicals is now a paradigm of contribution to the safeguard of public health. As pointed out by the ICH concept paper E14/S7B, there is a need for science-based frameworks that allow a better design, conduction, and interpretation of nonclinical and toxicity tests, particularly, in order for those assays to influence nonclinical and clinical evaluations and decisions better. Critical issues related to the performance and predictive values of nonclinical testing were highlighted and discussed in this article, specifically, to help pharmacologists, toxicologists, and regulators in the evaluation of the reliability of such tests, and basing the prospective decisions on the true predictivity of selected screening tests. This review addressed two common mistakes in drug and chemical testing, namely, (a) the assumption of either sensitivity or specificity as automatically “predictive,” and (b) the reporting of the predictive values disregarding a truly representative prevalence. This review also discussed a statistical basis to apply for (industry standpoint) or grant (regulatory standpoint) authorization for the waiving of selected nonclinical tests. Furthermore, this review can be guiding for those who are entering into the field of drug and chemical testing. Through application, investigation, and enhancement of the conceptual framework discussed in this review, nonclinical testing is expected to provide a higher contribution to drug and chemical development, regulatory science, and public health.

Evidence and recommendations for the use of segmental motion testing for patients with LBP – A systematic review

BackgroundAssessment of low back pain (LBP) includes segmental motion tests. Although often used in clinical practice, the validity, inter- and intra-rater reliability of such tests in individuals with LBP are not universally accepted, making it difficult to interpret findings in clinical practice. ObjectiveThe purposes of this study were to determine the validity and reliability of segmental motion tests for patients with LBP and to give reasoned recommendations for their use in practice. DesignSystematic review. MethodsA systematic literature research was conducted of databases PubMed, LIVIVO and Cochrane library. The included studies were appraised for quality by using QUADAS-2 and an adapted version of QAREL tools. Results of studies were appraised to give reasoned recommendations taking quality criteria into account. ResultsThirteen studies were included covering passive accessory intervertebral motion testing (PAIVMs), passive physiological intervertebral motion testing (PPIVMs) and the prone instability test (PIT). The risk of bias of studies ranged from high to low. When used in isolation, specificity of PAIVMS and PPIVMs was generally high and sensitivity poor. Reliability was overwhelming poor for both. Reliability of the PIT was inconsistent. None of these assessments can be strongly recommended when used in isolation. ConclusionThe evidence regarding validity and reliability of segmental motion testing is poor and clinical use of stand-alone tests cannot be recommended. Superiority of the combination of tests as a test battery or with other clinical information needs further investigation.

Latent class models for medical diagnostic tests in multicenter trials

Medical diagnostic tests must enjoy appropriate validity and high reliability in order to qualify as adequate assessment tools. Without a gold standard test, available medical diagnostic tests are not perfect; hence, the reliability of such tests must be evaluated precisely. Kappa coefficient statistics are often utilized to assess reliability of tests when there are two or more medical diagnostic tests. However, the statistics are imprecise for a typical case when the prevalence rate of a target disease is unknown. Although latent class models could be used to assess reliability, the models cannot estimate reliability in the case of two tests, due to unidentifiability or the lack of degrees of freedom. An alternative approach to assess reliability for the case of two tests is stratifying a two-by-two contingency table under the assumption that sensitivities and specificities between the two tests be equal over all strata and that prevalence rates in the strata be different from each other. Because stratification is basically a multi-sample analysis, it should not be applied to the situation where subsamples (i.e., centers) are randomly selected from a larger population. In this article, a type of mixed-effect model is proposed to evaluate the reliability of two tests for trials in randomly selected multiple centers. Several types of distributions for prevalence rates over subpopulations are considered. Simulation studies show that our proposed method performs nicely. Analysis of real data is also reported.

Gold and diagnostics—some staggering numbers

Many of you probably know that gold nanoparticles enable many different types of diagnostic technologies. From simple pregnancy tests to FDA-approved molecular diagnostic kits for clinical use, these tiny particles of gold ensure the accuracy and reliability of such tests all over the world. However, what you may not be aware of is just how many of these tests are used on a yearly basis. It is something that I have long wanted to know more about, so over the last couple of months, I have been looking into the market in some depth. The pregnancy testing kit is an example of a rapid diagnostic test (RDT). RDTs allow the reliable diagnosis of a condition or illness by individuals who may not be skilled in laboratory techniques or have access to advanced instrumentation. They are cheap and portable, making them particularly useful in remote or resourcepoor parts of the world. One condition where early diagnosis is critical to a successful therapeutic outcome is malaria. There are many angles to this, whether it be simply catching and treating the disease earlier, through to differentiating people who are suffering from a simple fever rather than malaria itself (hence avoiding unnecessary treatment with antimalarial drugs and lowering the development of drug resistance in communities). Thanks to the work of many NGOs and ministries of health around the world, reliable malaria RDTs now reach the frontline and are helping to combat this deadly disease. Now, this is where the staggering numbers come in. In a discussion I had with colleagues at the Foundation for Innovative New Diagnostics, I asked if they had any feeling for how many of these tests were used on a yearly basis. The answer I got was 155 million. In 2011, 155 million malaria RDTs were sold for use around the world. To the best of our knowledge, each and every one of these tests uses a minute quantity of gold to help ensure the accuracy and stability of the kit.We decided to try and bring this story to life and developed a short film to show how these tests impact communities around the world. If you are interested, please visit the site http://www.gold.org/video/play/gold_for_health/. So for the next generation of gold technologies, we have another excellent issue of Gold Bulletin for the second quarter of 2013, comprising the usual diverse range of papers, reviews and literature highlights. Thanks as always to the authors for their submissions and to our reviewers for their hardwork. Please visit our website at http://www.springer.com/materials/special+types/ journal/13404 to sign up for alerts or submit your work.

SSA-MOA: a novel CTC isolation platform using selective size amplification (SSA) and a multi-obstacle architecture (MOA) filter

Circulating tumor cells (CTCs) have gained increasing attention as physicians and scientists learn more about the role these extraordinarily rare cells play in metastatic cancer. In developing CTC technology, the critical criteria are high recovery rates and high purity. Current isolation methods suffer from an inherent trade-off between these two goals. Moreover, ensuring minimal cell stress and robust reproducibility is also important for the clinical application of CTCs. In this paper, we introduce a novel CTC isolation technology using selective size amplification (SSA) for target cells and a multi-obstacle architecture (MOA) filter to overcome this trade-off, improving both recovery rate and purity. We also demonstrate SSA-MOA's advantages in minimizing cell deformation during filter transit, resulting in more stable and robust CTC isolation. In this technique, polymer microbeads conjugated with anti-epithelial cell adhesion molecules (anti-EpCAM) were used to selectively size-amplify MCF-7 breast cancer cells, definitively differentiating from the white blood cells (WBCs) by avoiding the size overlap that compromises other size selection methods. 3 μm was determined to be the optimal microbead diameter, not only for size discrimination but also in maximizing CTC surface coverage. A multi-obstacle architecture filter was fabricated using silicon-on-glass (SOG) technology-a first such application of this fabrication technique-to create a precise microfilter structure with a high aspect ratio. The filter was designed to minimize cell deformation as simulation results predicted that cells captured via this MOA filter would experience 22% less moving force than with a single-obstacle architecture. This was verified by experiments, as we observed reliable cell capture and reduced cell deformation, with a 92% average recovery rate and 351 peripheral blood leukocytes (PBL) per millilitre (average). We expect the SSA-MOA platform to optimize CTC recovery rates, purity, and stability, increasing the sensitivity and reliability of such tests, thereby potentially expanding the utilization of CTC technologies in the clinic.

Method variables affecting the bioaccessibility of arsenic in soil

Arsenic bioaccessibility tests are now being commonly used in risk assessment. However, concerns remain about the reliability of such tests because the bioaccessibility of arsenic from soil may be susceptible to soil composition (including iron concentration), as well as method considerations such as varying liquid-to-solid ratios and the chosen buffer system. In this study, arsenic-contaminated tailings and soils were tested to compare two bioaccessibility methods: one that uses glycine as a buffer, and a second that is more physiologically based. With the glycine-buffered method, arsenic and iron bioaccessibility increased in the presence of a higher buffer concentration at higher liquid-to-solid ratios, whereas the results of physiologically-based tests were unaffected by variations in these parameters. In the glycine-buffered system, interactions between iron and glycine may influence the concentration of arsenic in solution, which may not be consistent with human gastrointestinal conditions. The choice of a physiologically-based method may be more appropriate to achieve representative arsenic bioaccessibility values toward estimating risks to human health.

Reproducibility of an isokinetic eccentric muscle endurance task

Despite the widespread use of isokinetic eccentric muscle endurance protocols, no research has examined the absolute and relative reliability of such tests. The aim of this study was to examine the reliability of an isokinetic eccentric knee muscle endurance task. Fifteen healthy untrained males volunteered to take part in the study and written informed consent was obtained. The procedures received approval from the University Research Ethics Committee. Participants visited the laboratory on three separate occasions: 2 weeks before testing to familiarize them with the experimental procedures, and on two separate occasions, 2 weeks apart and at the same time of day. Isokinetic eccentric knee extension and flexion movements of the dominant limb were performed using a calibrated dynamometer (Biodex System 3). Range of motion during testing was set using voluntary maximal full extension (0 rad) to 1.57 rad of knee flexion and testing was conducted at 1.56 rad · s−1. Participants performed four maximal efforts to determine maximal peak torque. After 2 min rest, participants completed the all-out endurance test of 50 continuous eccentric repetitions. Data were gravity corrected and windowed to only include constant velocity periods. Repeated-measures analyses of variance were used to examine differences in maximal peak extension and flexion torque and the maximal torque measurement recorded during the endurance test. Absolute and relative reliability of the torque fatigue index, work fatigue index, and total work were assessed through calculation of intra-class correlation coefficients, coefficients of variation, and absolute 95% limits of agreement using the methods described by Bland and Altman (1986). Differences between the strength test and the endurance trial for peak torque were found to be non-significant for both quadriceps (323 vs. 323 N · m) and hamstrings (183 vs. 178 N · m). The intra-class correlation coefficients revealed significant (P<0.05) positive moderate to strong correlations (r=0.44–0.94) across repeated trials for all parameters except hamstring torque fatigue (P=0.11) and hamstring work fatigue index (P=0.08). Coefficients of variation ranged from 6% to 48% and were large for the work fatigue index and torque fatigue index but acceptable for total work for both the extensors and flexors. The 95% limits of agreement indicated systematic bias in repeated trials for both the work fatigue index and torque fatigue index for extensors and flexors, ranging from −3% to −10%, with less fatigue evident in the second test. There was also systematic bias for total work, with more work being performed during the second than the first test for both extensors and flexors. The random error was large for all variables and there was greater random error in the hamstrings compared with the quadriceps. Together with moderate to strong intra-class correlation coefficients and large coefficients of variation, the data suggest that there is small systematic bias in repeated eccentric muscle actions for both the quadriceps and hamstrings, although the random error was large despite habituation procedures. Therefore, data from an isokinetic eccentric muscle endurance task should be viewed with some caution even when participants receive considerable habituation before assessment.

Benford's Law and Macroeconomic Data Quality

This paper examines the usefulness of testing the conformity of macroeconomic data with Benford's law as indicator of data quality. Most of the macroeconomic data series tested conform with Benford's law. However, questions emerge on the reliability of such tests as indicators of data quality once conformity with Benford's law is contrasted with the data quality ratings included in the data module of the Reports on the Observance of Standards and Codes (data ROSCs). Furthermore, the analysis shows that rejection of Benford's law may be unrelated to the quality of statistics, and instead may result from marked structural shifts in the data series. Hence, nonconformity with Benford's law should not be interpreted as a reliable indication of poor quality in macroeconomic data.

Benford’s Law and Macroeconomic Data Quality

This paper examines the usefulness of testing the conformity of macroeconomic data with Benford's law as indicator of data quality. Most of the macroeconomic data series tested conform with Benford's law. However, questions emerge on the reliability of such tests as indicators of data quality once conformity with Benford's law is contrasted with the data quality ratings included in the data module of the Reports on the Observance of Standards and Codes (data ROSCs). Furthermore, the analysis shows that rejection of Benford's law may be unrelated to the quality of statistics, and instead may result from marked structural shifts in the data series. Hence, nonconformity with Benford's law should not be interpreted as a reliable indication of poor quality in macroeconomic data.

Reliability of accessory motion testing at the carpal joints

The testing of accessory motion has become a very important part of manual therapy practice. Its value is in assessing whether joint mobility is ideal or impaired. Despite its use, there is little evidence in the literature to support the reliability of such testing. Most of the research carried out on accessory motion testing has focused on the spine. In view of this we decided to evaluate the intra- and interrater reliability of accessory motion testing of carpal joints. Two skilled therapists tested the available motion and the end-feel response of carpal joints in 30 students and 15 patients on two separate occasions. Pain scores were also obtained. In students a moderate to good percentage of agreement [67–97%] was obtained for motion testing. In patients the percentage of agreement ranged from 60% to 100% and weighted kappa values were between 0.33 and 1.0. Intrarater reliability was better than interrater reliability in both groups. Intra- and interrater agreement on end-feel was very good. Overall, the reliability of accessory motion testing of carpal joints was acceptable. The results suggest that this form of testing can be valuable in the training of manual therapists and in clinical practice.

The reliability of selected motion- and pain provocation tests for the sacroiliac joint

The objective of the study was to assess inter-rater reliability of one palpation and six pain provocation tests for pain of sacroiliac origin. The sacroiliac joint (SIJ) is a potential source of low back and pelvic girdle pain. Diagnosis is made primarily by physical examination using palpation and pain provocation tests. Previous studies on the reliability of such tests have reported inconclusive and conflicting results. Fifty-six women and five men aged 18–50 years old were included in the study. Fifteen patients had ankylosing spondylitis; 30 women had post partum pelvic girdle pain for more than 6 weeks; and 16 people had no low back or pelvic girdle pain. All participants were examined twice on the same day by experienced manual therapists. Percentage agreement and kappa statistic were used to evaluate the tests reliability. Results showed percentage agreement and kappa values ranged from 67% to 97% and 0.43 to 0.84 for the pain provocation tests. For the palpation test the percent agreement was 48% and the kappa value was −0.06. Clusters of pain provocation tests were found to have good percentage agreement, and kappa values ranged from 0.51 to 0.75. In conclusion this study has shown the reliability of the pain provocation tests employed were moderate to good, and for the palpation test, reliability was poor. Clusters out of three and five pain provocation tests were found to be reliable. The cluster of tests should now be validated for assessment of diagnostic power.

Can completive and durative adverbials function as tests for telicity? Evidence from English and Chinese

Telicity is an important concept in the study of aspect. While the compatibility tests with completive and durative adverbials have long been in operation as a diagnostic for telicity, their validity and reliability have rarely been questioned. This article critically explores the validity and reliability of such tests and discusses such temporal expressions in English and Chinese on the basis of written and spoken corpora of the two languages and proposes a scheme of usage categories of completive and durative adverbials with their respective proportions, which is adequately explanatory of the phenomena observed in attested language use and enables compatibility tests with completive and durative adverbials to achieve improved accuracy and reliability.

The Effects of Skin Temperature and Testing Site on Blood Glucose Measurements Taken by a Modern Blood Glucose Monitoring Device

Modern blood glucose (BG) monitoring devices (e.g., InDuo [LifeScan, Inc., Milpitas, CA]) require very low blood volumes, allowing for testing at sites other than the traditional fingertip, but the reliability of such testing has not been fully elucidated. The aim of this randomized study was to compare the effects of cold/warm skin temperature combined with alternative site (forearm) testing versus conventional fingertip measurements on fasting and postprandial conditions. The study population consisted of 19 patients who had previously used InDuo for 6 weeks. Four simultaneous (within 1 min) BG readings (left and right forearm and fingertips) were obtained from each patient 15, 10, and 5 min before eating. Ten minutes before eating, the patient immersed one arm in cold water (15.5 degrees C) and the other in warm water (35 degrees C). At time 0 min arms were removed from water baths, and the patient was offered a standard meal (duration 15 min). Arms were again immersed in water baths, and BG was measured from the same locations 20 min after eating and at subsequent 15-min intervals for 185 min. The effects of site testing and temperature were assessed in this period by identifying maximum BG concentrations (C (max)) and time to C (max) (T (max)). Significantly lower Cmax values were observed for (1) cold forearm versus cold fingertip (mean Delta 28.6 mg/dL, P < 0.001), (2) warm forearm versus warm fingertip (mean Delta 12 mg/dL, P = 0.028), (3) cold fingertip versus warm fingertip (mean Delta 17.2 mg/dL, P = 0.002), and (4) cold forearm versus warm forearm (mean Delta 33.7 mg/dL, P < 0.001). Significantly longer Tmax values were reported for cold forearm versus warm forearm (mean Delta 22.4 min, P < 0.001) and cold forearm versus cold fingertip (mean Delta 20 min, P < 0.001). These results demonstrate that cold skin and forearm conditions significantly underestimate BG concentrations and delay T(max) compared with warm skin and fingertip measurements.

The Antisocial Police Personality: A View from the Inside

It is argued from a psychiatric standpoint that persons who meet diagnostic criteria for Antisocial Personality Disorder, as defined by the Diagnostic and Statistical Manual of Mental Disorders (DSM‐IV), have a decreased likelihood of existing within the police population. It is claimed that through psychological testing and background checks, police departments are better able to filter out unsuitable applicants. However, the less‐than‐perfect reliability of such tests, as well as loose entrance requirements by individual police departments, present opportunities for applicants with Antisocial Personality Disorder to make their way into policing. Simply, there is no guarantee that these individuals do not or cannot exist within the police population. This research will suggest that police officers with traits of Antisocial Personality Disorder exist, that the types of behavior displayed have become increasingly violent, and the possibility that such traits may well have been acquired through the police subculture and its easy access to deviance. This insight is offered by the one of the authors who is retired from the New Orleans Police Department.

Assessment of human cancer risk: challenges for alternative approaches.

The ILSI/HESI Workshop on Alternatives to Carcinogenicity Testing aims to develop and apply new methods for assessment of potential carcinogenic risk to humans from various chemicals. The Workshop represents a major cooperative scientific effort. The long-term goals should be to greatly enhance the efficiency and reliability of such testing and to supplant, not just supplement, lifetime rodent bioassays. There are now well-established frameworks for risk assessment and risk management, putting risks into public health context and engaging stakeholders. The Lave-Omenn value-of-information model provides a useful way to assess the social costs and benefits of different strategies for testing large numbers of chemicals.