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PubMed1992

A comparison of two criterion-referenced standard setting procedures for sports skills testing.

The application of criterion-referenced (CR) standard setting procedures in physical education has been limited to the examinee-centered model known as criterion groups. Alternative examinee-centered approaches are available but have not been applied in sport skills testing. The purpose of this study was to compare two examinee-centered models for setting performance standards for a sport skills test battery. CR performance standards were determined for the tennis skills test battery published in Tennis skills test manual (Hensley, 1989) using the borderline group (BG) (Livingston & Zieky, 1982) and criterion groups (CG) (Berk, 1976) models. The comparison of these two methods demonstrated that the CG method consistently produced performance standards that were lower than the BG method. In one instance the BG method produced a standard that was clearly unreasonable. Estimates of CR reliability for the CG standards (.76 less than or equal to P less than or equal to .93; .52 less than or equal to Kq less than or equal to .86) were higher than BG estimates (.55 less than or equal to P less than or equal to .84; .11 less than or equal to Kq less than or equal to .68). Although each method has strengths, neither is without problems. Results from this study suggest these two methods might be combined to minimize the problems associated with each. This combined method should produce standards with improved accuracy, validity, and reliability.

Adult↗
PubMed1997

Standards for radioiodines.

The National Institute of Standards and Technology, NIST (formerly National Bureau of Standards), is the nation's standards laboratory for civilian technology. NIST develops and maintains the nation's physical measurement standards for medical therapy and diagnostics. For the past 50 years, NIST has developed radioactivity Standard Reference Materials (SRMs) for radioiodines as well as decay-scheme data and test methods for use by the radiopharmaceutical manufacturers in their quality assurance and quality control at the point of manufacture. Methods of standardizing radioiodines include 4 pi beta-gamma coincidence counting (131I), 4 pi beta-gamma anti-coincidence counting (129I), 4 pi(e,x)-gamma coincidence counting (123I), and x-gamma sum peak coincidence counting (125I). NIST also uses sources standardized by these techniques to calibrate re-entrant ionization chambers (dose calibrators) and scintillation counters. SRMs of 131I and 125I are now available on an annual basis, and the long-lived 129I has recently been reissued.

Iodine Radioisotopes↗
PubMed1995

Evaluation of internal standards for the analysis of amphetamine and methamphetamine.

Deuterium-labeled analogues are available for a variety of drugs, but the amphetamines (amphetamine and methamphetamine) have more options available than any other drug. The analytical method and circumstances of its use can have a significant impact on the decision of what is the best internal standard to use. More than one method can give acceptable results; however, some circumstances can make a given internal standard a poor choice for a particular analysis. Increased choices of available candidates make the evaluation of an internal standard even more difficult. Thorough evaluation of the available options is a major undertaking and is presented here to assist laboratories in selection of the most appropriate internal standard for their individual needs. All commercially available deuterated analogues to amphetamine and methamphetamine were evaluated as part of this study. in addition, nonisotopically labeled propylamphetamine was also evaluated for comparison purposes. The compounds were analyzed underivatized and derivatized with trifluoroacetic anhydride, pentafluoropropionic anhydride, heptafluorobutyric anhydride, and 4-carbethoxyhexafluorobutyryl chloride on HP-1, HP-5, and DB-I 7 capillary columns. Mass spectral analysis revealed that several of the internal standards were not viable for monitoring ions typically associated with selected ion monitoring analysis of amphetamine and methamphetamine. These included amphetamine-d3 (1-phenyl-2-aminopropane-3,3,3-d3) and amphetamine-d5 (phenyl-d5), neither of which exhibits three unique ions. The d3 standard shares the common ion at m/z 91, acid d5 (phenyl) shares the base peak ion with derivatized amphetamine. Although methamphetamine-d6 and methamphetamine-d10 show three unique ions, they do not allow monitoring of the ion fragments typically used for methamphetamine. Evaluation of the limit of detection, linear range, and within-run and between-run variability was accomplished for each viable internal standard.

Acetic Anhydrides↗
PubMed1991

The interobserver reliability of the revised American Spinal Injury Association standards for neurological classification of spinal injury patients.

To test the interobserver reliability of clinicians using the American Spinal Injury Association's 1989 revised "Standards for Neurological Classification of Spinal Injury Patients," two quizzes were given to 15 house officers and physician faculty members of a department of Physical Medicine and Rehabilitation. The first quiz consisted of five spinal cord injury cases of varying degrees of complexity. The participants were asked to classify each case with respect to sensory level, motor level, zone of injury and Frankel classification by using the original standards. Two months later, after a brief explanation of the significant changes in the revised standards, the same group was given five slightly different cases to classify. With the use of the 1989 revision of the standards, the percent correct improved for Frankel grade (65-81%), motor level (59-85%), sensory level (71-93%) and zone of injury (31-89%). Many of the same type of errors were repeated in both quizzes, i.e., T-12 and L-1 sensory level distinction and the classification of thoracic motor levels. We conclude that the interobserver reliability for the revised ASIA standards, although improved, continues to be less than optimal. We recommend that changes clarifying sensory levels near the inguinal ligament and motor level classification with very incomplete injuries be made in the standards. In addition, training methods should be developed to improve the interobserver reliability of the standards when they are used by clinicians and researchers.

Humans↗
PubMed2001

The use of volume standards in health services.

The ways in which volume standards are implemented by health services organizations are not clear. Therefore, the authors sought to evaluate the extent of use of volume standards, the purposes for which such standards were developed, and the sources of the standards in a sample of health services organizations. The authors found that volume standards were used widely by accrediting organizations, professional societies, and hospitals in their sample, but almost never by health maintenance organizations. Volume standards were used for ensuring adequate experience among residents, providing guidelines to residency programs, and privileging and credentialing physicians. Expert consensus appeared to be the usual source of volume standards.

Accreditation↗
PubMed1993

The International Standard for Thyroxine Binding Globulin.

OBJECTIVE: Thyroxine binding globulin is the major thyroid hormone binding and transport protein of the plasma, and its quantitative estimation is therefore of clinical importance. The objectives of the present study were to prepare and ampoule a preparation of thyroxine binding globulin suitable to serve as an international standard, to confirm the suitability of the preparation in a multi-centre collaborative study, and to assign an ampoule content. DESIGN: The collaborative study was designed with the following aims: (1) to compare the candidate preparation with local standards; (2) to calibrate the preparation with local standards and to confirm the assigned ampoule content; (3) to assess the stability of the ampouled preparation. MEASUREMENTS AND RESULTS: Thyroxine binding globulin was purified by a combination of affinity and conventional chromatography. Analysis by gel electrophoresis, N-terminal sequencing and electrospray mass spectroscopy showed the preparation to be > 99% pure and to have a structure consistent with the known structure of thyroxine binding globulin. Thyroxine binding globulin assays performed in the multi-centre collaborative study indicated that the preparation behaved as thyroxine binding globulin when compared to local standards and that the ampoule content was consistent with that assigned on the basis of physicochemical measurements of protein concentration. CONCLUSIONS: The thyroxine binding globulin preparation coded 88/638 was established by the Expert Committee on Biological Standardization of the World Health Organization as the International Standard for Thyroxine Binding Globulin, 30.0 International Units per ampoule, with the additional information that for the preparation in 88/638, 1 IU is equivalent to 1 microgram. The preparation is available from the National Institute for Biological Standards and Control.

Chromatography, Affinity↗
PubMed1990

Standards for the application of X-ray microanalysis to biological specimens.

A review on the subject of compounds used as standards for biological X-ray microanalysis is presented. The general approach used for standardization has been to use standards which resemble the specimen closely in composition. Thus, standards based on proteins have been used for analysis of quench-frozen cryosectioned specimens, whereas standards based on embedding resins have been used for resin-embedded material. The properties of, and problems associated with, each type of standard are recognized and have been well documented. The choice and analysis of biological material. Attention is drawn to the fact that the problems associated with any quantification procedure need to be kept in mind when analysis of standards is undertaken.

Animals↗
PubMed2000

Comparison of dosimetry calibration factors at the NRCC and the NIST. National Research Council of Canada. National Institute of Standards and Technology.

In early 1998, three transfer ionization chambers were used to compare the air-kerma and absorbed-dose-to-water calibration factors measured by the National Research Council of Canada (NRCC) and the National Institute of Standards and Technology (NIST). The ratios between the NRCC and NIST calibration factors are 0.9950 and 1.0061 in the case of the absorbed-dose-to-water and air-kerma standards, respectively. In the case of the standard of absorbed dose to water, the combined uncertainty of the ratio between the standards of the two laboratories is about 0.6% and consequently, the observed difference of 0.5% is not significant at the one sigma level. In the case of the standard of air kerma, the combined uncertainty of the ratio between the standards of the two laboratories is about 0.4%, and so the observed difference of 0.61% is significant at the one sigma level. However, this discrepancy is due to the known differences in the methods of assessing the wall correction factor at the two laboratories. Taking into account changes implemented in the standards that form the basis of the calibrations, the present results are consistent with those of the previous comparison done in 1990/91. As a direct result of these differences in the calibration factors, changing from an air-kerma based protocol following TG-21 to an absorbed-dose-to-water based protocol following TG-51, would alter the relationship between clinical dosimetry in Canada and the United States by about 1%. For clinical reference dosimetry, the change from TG-21 to TG-51 could result in an increase of up to 2% depending upon the ion chamber used, the details of the protocol followed and the source of traceability, either NRCC or NIST.

Air↗
PubMed1996

Sex differences in weight in infancy and the British 1990 national growth standards.

OBJECTIVES: To determine if there is a sex difference in infancy in the new British national standards for weight (based on data from 1990). DESIGN: Weight data in a birth cohort were compared with the 1990 standards and Tanner and Whitehouse (1966) standards up to age 12 months. SETTING: Newcastle upon Tyne. SUBJECTS: 3418 term infants. RESULTS: Our cohort showed a mean difference in standard deviation scores of 0.42 between boys and girls (P < 0.0001) when compared with the 1990 standards. Two and a half times as many girls as boys had weights below the 3rd centile during the first year, with an equivalent excess of boys above the 97th centile (P < 0.0001). Similar results were found with Tanner and Whitehouse standards. CONCLUSIONS: These differences could result in substantial sex bias in the identification of poor growth in early childhood. The standards need modification.

Body Weight↗
PubMed1983

Standards versus standardised methods in enzyme assay.

In a trial of the Netherlands coupled external/internal quality control program a control serum and an enzyme standard were analysed over a period of eight weeks, five times each week. Five enzymes were determined: alkaline phosphatase, creatine kinase, lactate dehydrogenase, alanine aminotransferase, and gamma-glutamyltransferase. The measured values in the serum were converted to the standards. Those laboratories using the recommended methods also submitted their non-transformed serum values. The following standardisation techniques have been compared: (a) no standardisation of methodology but use of enzyme standards; (b) standardisation of methodology; (c) standardisation of methodology combined with use of an enzyme standard. Results were submitted to analysis of variance. Standardisation of methodology did not yield smaller interlaboratory variation than the standardisation with enzyme standards. In this trial a combination of both standardisation techniques yielded generally better results. Results for gamma-glutamyltransferase indicate that standardisation of substrate may be necessary apart from the use of an enzyme standard. The preparation of stable enzyme standards is stressed.

Alanine Transaminase↗
PubMed1999

The influence of antagonist standardization on wear.

For differences among materials to be easily detected, low variation in in vitro wear tests is desirable. The working hypothesis of this paper was that antagonists standardized for shape and size and according to materials would show mean values similar to those found in natural, non-standardized cusps, and that standardization would lead to a reduction in mean variation. First, the shapes and sizes of palatal cusps of non-erupted human upper third molars were measured. The cusp cupola was best described by the formula y = 0.001 x2 and was symmetrical around the axis of rotation. Up to 200 microm of the y-axis, this parabola corresponded best to a ball radius of 0.6 mm. Based on this information, standardized antagonists were fabricated from both human enamel and steatite. Wear in the occlusal contact area and the wear of opposing conventional ceramic and fine hybrid composite, respectively, were quantified in a computerized chewing simulator. As a control, natural human enamel cusps were used. Standardization of enamel cusps did not reduce the variation of the resulting wear compared with that of non-standardized enamel antagonists. Furthermore, standardization led to significantly different results both in the antagonists and in the opposing restorative materials. Thus, natural enamel antagonists are preferable for the simulation of wear in the occlusal contact area.

Analysis of Variance↗
PubMedDate not supplied

Early elementary curricular alignment and teacher perspectives on standards-based reform.

The author investigated the alignment of reading instruction to Wisconsin Model Academic Standards for Reading, grades 1-4 (Wisconsin Department of Public Instruction, 1998a). Teachers in 18 hearing-only, 10 mixed (hearing and deaf students), and 8 deaf-only classrooms were study participants. Teacher groups demonstrated equal alignment to the standards. The study also measured teachers' views on standards. Teachers in hearing-only and deaf-only classrooms scored higher on a scale measuring receptivity toward standards than teachers in mixed classrooms. Teachers in hearing-only classrooms considered the standards good guidelines though perhaps too prescriptive. Teachers in deaf-only and mixed classrooms viewed standards as tools to ensure equity for students but also focused on challenges like the emphasis on phonetics and their need to include sign in deaf students' instruction. Limitations include the challenge of generalizing standards-based analysis, the small number of participants, and use of self-report measures of classroom instruction.

Achievement↗
PubMed1993

Establishment of the second international standards for porcine and human calcitonins: report of the international collaborative study.

The biological potency of calcitonins in clinical use in long-term treatment of Paget's disease of bone and, increasingly, in osteoporosis is usually expressed international units defined by the relevant World Health Organization international reference preparation. The international reference preparations for porcine and human calcitonins were ampouled in 1970 and stocks are now exhausted. Replacement standards were ampouled in 1989 and have been evaluated and calibrated by an international collaborative study comprising 16 laboratories in 12 countries. Evaluations included high-performance liquid chromatography and in vitro bioassay; calibration of each new ampouled preparation in terms of its international reference preparation was by in vivo rat hypocalcaemia bioassay. On the basis of the results of the study and with the agreement of the participants, replacement standards were established by the Expert Committee on Biological Standardization of the World Health Organization in 1991: the international standard for porcine calcitonin (ampoule code 89/540), with an assigned potency of 0.8 international units per ampoule, and the international standard for human calcitonin, with an assigned potency of 17.5 international units per ampoule. Both international standards appeared to be sufficiently stable to serve as the international standards for in vivo biological assays. Comparison of the two species of calcitonin in the same hypocalcaemia assay showed that they were approximately equipotent when the doses were given intravenously but that the human peptide was four- to sixfold more potent than porcine calcitonin when doses were given subcutaneously, emphasizing the need to compare "like with like".

Animals↗
PubMed2001

Cost-effective method to synthesize a fluorescent internal DNA standard for automated fragment sizing.

We describe a simple and cost-effective method for the synthesis of an internal fluorescently labeled DNA standard for fragment sizing using an automated DNA sequencer. A set of primer pairs labeled with ROX was developed to amplify 12 DNA fragments, 58-417 bp, derived from a conserved region of plant chloroplast DNA. These amplified fragments were mixed together, constituting a fluorescent internal DNA size marker. The precision of the size standard was evaluated by estimating the size of 20 alleles that were amplified at four dinucleotide microsatellite loci with the synthesized size standard and the commercial internal sizing standard, GeneScan Rox500. A number of intra-gel and inter-gel comparisons were run, and an analysis of variance was carried out. No significant difference was observed between the size estimates obtained with the synthesized DNA standard and the commercial standard. This facile and general PCR-based method for the synthesis of internal standards allows for significant savings in the implementation of large genotyping experiments using microsatellite or AFLP markers.

Base Sequence↗
PubMed1994

Using Hawksley random zero sphygmomanometer as a gold standard may result in misleading conclusions.

We combined a database of paired blood pressure measurements taken using the Hawksley random-zero sphygmonanometer and a standard mercury sphygmomanometer and a database of paired measurements made on a SpaceLabs 90202 ambulatory blood pressure recorder and standard sphygmomanometer to determine how the SpaceLabs 90202 would have fared if it had been assessed against the Hawksley random-zero sphygmomanometer instead of a standard sphygmomanometer. The pooled database contained 255 triplicate readings. Using the standard sphygmomanometer as gold standard, the Spacelabs had a median error of 2 mm/Hg for both systolic and diastolic. Against the Hawksley random-zero sphygmomanometer, median error was -3 mm systolic and -6 mm diastolic. The proportion of errors > 10 mm rose from 11% (systolic) and 9% (diastolic) with the standard sphygmomanometer to 16% and 29% with the Hawksley random-zero sphygmomanometer. Because it underestimates systolic and diastolic pressures, the use of the Hawksley random-zero sphygmomanometer as a gold standard may have resulted in misleading conclusions about performance of some automated BP recorders.

Adult↗
PubMed2005

The role of standards in the development and implementation of clinical laboratory tests: a domestic and global perspective.

In the field of clinical laboratory medicine, standardization is aimed at increasing the trueness and reliability of measured values. Standardization relies on the use of written standards, reference measurement procedures and reference materials. These are important tools for the design and validation of new tests, and for establishing the metrological traceability of diagnostic assays. Their use supports the translation of research technologies into new diagnostic assays and leads to more rapid advances in science and medicine, as well as improvements in the quality of patient care. The various standardization tools are described, as are the procedures by which written standards, reference procedures and reference materials are developed. Recent efforts to develop standards for use in the field of molecular diagnostics are discussed. The recognition of standardization tools by the FDA and other regulatory authorities is noted as evidence of their important role in ensuring the safety and performance of in vitro diagnostic devices.

Chemistry, Clinical↗
PubMed2005

Developing a cell line standard for HER2/neu.

Advancements in medical genetics are resulting in the identification of key molecules in the pathways that lead to carcinogenesis. With these discoveries, drugs are developed that target a protein or block a particular molecular pathway with the potential to bring about disease regression. The HER2/neu tyrosine kinase receptor is one such target. Therapy based on the humanised monoclonal antibody, trastuzumab, targets HER-2/neu and inhibits the growth of HER2/neu-overexpressing breast cancer cells. Assays for markers to HER2/neu are forerunners of many more predictive assays that are likely to enter the clinical arena in the near future, many of which will require quantitative analysis. In the field of tissue based assay systems controversies are well documented on the lack of reproducibility in the immunohistochemical analysis HER2/neu. The problems encountered to date lye with the difficulty in reliably standardising the immunohistochemical assay. One of the first steps in addressing this issue is to develop a standard reference material against which the 'variable' of assay sensitivity for HER2/neu can be accurately gauged. Work in the United States and Europe aimed at providing a standard reference material for HER2/neu has already commenced. Preliminary work conducted in Europe shows that development of a standard comprised of cell lines is feasible and when employed as part of an external quality assurance programme, results in significant improvement in the numbers of clinical laboratories achieving appropriate results. In the United States it has been proposed that two standards consisting of well characterized cell lines will be produced, one a National Institute of Standards and Technology (NIST)--certifiable standard, and the other a commercially developed standard for use in all HER2/neu testing. The aim is that this approach will act as a template for other important predictive markers of the future.

Biomedical Engineering↗
PubMed1999

Impact of DNA typing on standards and practice in the forensic community.

This article reviews the history of DNA-based human identification from its inception in 1985. Since the development of the technology, experts called for setting of standards and use of proficiency tests for quality assurance measures. The response of the National Institute of Standards and Technology to DNA forensic standards needs was catalyzed by the Technical Working Group on DNA Analysis Methods, sponsored by the Federal Bureau of Investigation with funding provided by the National Institute of Justice. Standard reference materials were developed for the original technologies used in DNA identification and for the newer polymerase chain reaction-based technologies. Adoption of recommended standards developed through the Federal Bureau of Investigation-commissioned DNA Advisory Board show the acceptance of National Institute of Standards and Technology standards for calibration of laboratory protocols. New technologies will require a process of validation and continued testing through the use of proficiency tests, such as those provided through the College of American Pathologists. Robotics and parallel processing of samples will lead to increased efficiency in DNA testing. The use of DNA data banks of convicted felons will increase dramatically with the the Federal Bureau of Investigation's national implementation of a computerized identification system known as the Combined DNA Index System. This system that will make major use of short, tandem, repeat genetic systems and will be the major driver of technology for the next 5 to 10 years. Finally, sample collection and training are of major concern for those who look at the long-term impact of DNA testing in forensic laboratories.

DNA↗