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91.
Assessing students’ conceptions related to independence of events and determining probabilities from a sample space has been the focus of research in probability education for over 40 years. While we know a lot from past studies about predictable ways students may reason with well-known tasks, developing a diagnostic assessment that can be used by teachers to inform instruction demands the use of familiar and unfamiliar contexts. This paper presents the current work of a research team whose aim is to create a formative concept inventory with strong evidence of validity that uses a psychometric model to confidently predict whether a student exhibits one or more misconception across many items. We illustrate this process in this paper using a particular item with a context of a raffle aimed to measure whether a student reasons with misconceptions related to independence or equiprobability. The results of two aspects of the validity process: cognitive interviews to assess response processes on individual items, and a large-scale administration to examine internal structure of the concept inventory revealed difficulties in assessing students’ reasoning about these key probability concepts and trends in the prevalence of misconceptions across grades. Results can provide guidance for others aiming to develop assessments in mathematics education and also support further possibilities for research into understanding students’ reasoning about independence and sample space. 相似文献
92.
膨胀土胀缩性评价中有关问题的研究 总被引:3,自引:0,他引:3
膨胀土吸水膨胀、失水收缩,产生地表变形,进而导致建筑物破坏。本文就现行膨胀土胀缩性指标试验及地基变形量评价计算中有关问题进行了研究,认为以天然含水量为起始含水量测定土样胀缩率是不合适的,建议以缩限为起点进行膨胀试验,以胀限为起点进行收缩试验,采用加荷膨胀量(而非卸荷膨胀量)参加有荷载下的膨胀率计算。膨胀土地基勘察必须结合场地条件分析可能影响土体含水量变化的因素,对同一工程采用几种方法评价,互相对比、参照。 相似文献
93.
94.
Peter S. Unger 《Accreditation and quality assurance》1998,3(9):373-376
The American Association for Laboratory Accreditation (A2LA) marks its 20th year of existence. Its major aim as a non-profit,
public service organization is to promote laboratory quality and competence. In terms of the number of current accreditations,
A2LA is the largest multidiscipline laboratory accreditation body in the United States and the fourth largest in the world.
An overview of current activities and status is provided. 相似文献
95.
《高分子材料》课程是高分子材料与工程专业的一门必修课,是学生了解和掌握高分子材料专业知识的基础课程。本文通过对高分子材料与工程专业的《高分子材料》课程教学方式和考核方式的改革,探索了在课程中引入材料重要性讨论、市场调研、大作业演讲、企业和行业协会人员进教室等方式提高学生服务地方能力。在加入这些实践元素的同时,探索了对考核方式的改进和完善,激发了学生的学习兴趣,提高了学习效果。这种教学模式值得在本专业相似的课程中推广。 相似文献
96.
建立了微波消解电感耦合等离子体-原子发射光谱法(ICP-AES)测定中成药中Cu、Pb、Cd和Cr重金属含量的方法,并用该法测定了14种清热解毒类中成药中Cu、Pb、Cd和Cr等重金属的含量,并对中成药中重金属的污染状况进行了评价。方法的加标回收率为96.7%—108.0%,相对标准偏差(RSD)值小于5.4%。实验结果表明,中成药中Cr和Cd污染严重,没有被Cu和Pb污染。 相似文献
97.
98.
Bonnie Soman 《Journal of voice》1997,11(3):285-294
This investigation evaluated the effect of method of elicitation onthe maximum sustained durations of /s/, /z/, and /a/ in eighty female subjects. The effect of order of elicitation on the maximum sustained durations of /s/ and /z/, and the effects of method and order of elicitation on the s/z ratio, were analyzed as well. Comparisons of three methods of measuring maximum phoneme duration (MPD) were performed. This study found method of elicitation of MPD to have an effect on the maximum sustained durations of /s/, /z/, and /a/ but not on the s/z ratio. The three methods of measuring MPD were found to correlate highly with one another. Results of this study point to the need for standardized procedures for elicitation of MPD. 相似文献
99.
Håkan Källgren Margreet Lauwaars Bertil Magnusson Leslie Pendrill Phillip Taylor 《Accreditation and quality assurance》2003,8(12):541-547
There is increasing interest in the role of measurement uncertainty in conformity assessment, particularly where measurements are in support of fair trade, health & safety and the environment. A lack of clarity, however, in treating measurement uncertainties and in setting specification limits for compliance may sometimes lead to drastic consequences. Examples concerning conformity assessment, particularly in the measurement of trace quantities (Cd in plastics and antibiotic trace residues in shrimps), are amongst cases identified in the ongoing EU project MetroTrade, which can be significant impediments to international trade. This paper considers the present status of the role of measurement uncertainty in conformity testing, covering both recent work in international standardisation and physical metrology (e.g. OIML recommendations on weighing). One conclusion is that, while much has been achieved, there still exists some work to be done in order to facilitate acceptance of conformity from both customer and supplier and avoid perceived barriers to trade and serious international trade disputes.Presented at the MetroTrade Workshop on Traceability and Measurement Uncertainty in Testing, 30–31 January 2003, Berlin, GermanyAn erratum to this article can be found at 相似文献
100.
S. Z. Cekan 《Accreditation and quality assurance》2002,7(2):73-76
A dedicated External Quality Assessment (EQA) system for immunoassays of reproductive hormones (LH, FSH, prolactin, hCG, progesterone,
estradiol, testosterone) and cortisol was developed. This catered for the needs of a group of laboratories conducting collaborative
research with the WHO in the field of human reproduction. This system was designed to provide the maximum information on assay
quality with the final aim of achieving and maintaining the highest possible comparability in monitored multi-center clinical
studies. The EQA was based on the assays of 32 control samples per year in 4 quarterly assay runs and the evaluation of the
following parameters: bias, between-run imprecision within a laboratory, number of outliers, frequency of returned assays
of control samples, and between-laboratory imprecision. The data obtained were combined in a performance index for each laboratory,
EQA run, and analyte. This index was then subjected to ranking. It may be assumed that the EQA system contributed to improvements
of analytical work and/or the maintenance of a high assay quality in participating laboratories.
Received: 26 July 2001 Accepted: 9 November 2001 相似文献