Applications of Hadamard transform-gas chromatography/mass spectrometry to the detection of acetone in healthy human and diabetes mellitus patient breath.

The Hadamard transform-gas chromatography/mass spectrometry (HT-GC/MS) technique was successfully employed to detect acetone, a biomarker for diabetes mellitus (DM) prediction, in human breath. Samples of exhaled breath were collected from four DM patients (one type-I and three type-II) and eight volunteers (nondiabetic healthy subjects), respectively. The gas samples, without any pretreatment, were simultaneously injected into a GC column through a Hadamard-injector based on Hadamard codes.

NBDE Part II practice analyses: an overview.

The Standards for Educational and Psychological Testing emphasize the importance of documenting and describing the procedures followed in developing valid test content. As a result, the Joint Commission on National Dental Examinations, the testing agency responsible for administering the National Board Dental Examination Part I and Part II, routinely communicates information about the validity of Part II to dental schools and other communities of interest. Since 2000, the content of Part II has been validated through the use of three practice analyses.

Assessing context effects on test validity of the National Board Dental Examination Part I.

In support of actions taken by the Joint Commission on National Dental Examinations, two changes--the inclusion of testlet items and the random presentation of items in an interdisciplinary format--were made to enhance the test validity of the National Board Dental Examination Part I in 2007. As a result, the examination was changed from a conjunctive to a comprehensive format. It was assumed that validity would be enhanced with regard to the examination's internal structure, while not disturbing item performance and examinee score.

Using Rasch analysis to construct a Clinical Problem-Solving Inventory in the dental clinic: a case study.

A 28-item inventory was developed to measure the clinical problem-solving abilities of 3rd and 4th year dental students. The judgments of 57 expert raters (dental-school faculty) from four dental schools used the inventory to evaluate 183 dental students on a 5-point rating scale. The Rasch measurement model was employed to examine the psychometric properties and construct validity of this inventory.

Examining item difficulty and response time on perceptual ability test items.

This study examined item calibration stability in relation to response time and the levels of item difficulty between different response time groups on a sample of 389 examinees responding to six different subtest items of the Perceptual Ability Test (PAT). The results indicated that no Differential Item Functioning (DIF) was found and a significant correlation coefficient of item difficulty was formed between slow and fast responders. Three distinct levels of difficulty emerged among the six subtests across groups.