Computer Adaptive Test Stopping Rules Applied to The Flexilevel Shoulder Functioning Test.

Computerized adaptive testing (CAT) is an attractive alternative to traditional paper-and-pencil testing because it can provide accurate trait estimates while administering fewer items than a linear test form. A stopping rule is an important factor in determining an assessments efficiency. This simulation compares three variable-length stopping rules-standard error (SE) of .3, minimum information (MI) of .7 and change in trait (CT) of .02 - with and without a maximum number of items (20) imposed. We use fixed-length criteria of 10 and 20 items as a comparison for two versions of a linear assessment. The MI rules resulted in longer assessments with more biased trait estimates in comparison to other rules. The CT rule resulted in more biased estimates at the higher end of the trait scale and larger standard errors. The SE rules performed well across the trait scale in terms of both measurement precision and efficiency.

Site-specific differences in gene expression of secreted proteins in the mouse lung: comparison of methods to show differences by location.

Studies on the effects of pulmonary toxicants on the lung often overlook the fact that site-specific changes are likely to occur in response to chemical exposure. These changes can be highly focal and may be undetected by methods that do not examine specific lung regions. This problem is especially acute for studies of the conducting airways. In this study, differential gene expression of secreted proteins in the lung by different methods of collection (whole lung, gross airway microdissection, and laser capture microdissection) and by airway levels (whole lobe, whole airway tree, proximal airways, airway bifurcations, and terminal bronchioles) was examined. Site-specific sampling approaches were combined with methods to detect both gene and corresponding protein expression in different lung regions. Differential expression of mRNA by both airway level and lung region was determined for Clara cell secretory protein, calcitonin gene-related peptide, uteroglobin-related protein 2, surfactant protein A, and surfactant protein C. Therefore, for maximal enrichment of mRNA and maximal ability to identify changes in mRNA levels in the diseased state or in response to chemical exposure, it is critical to choose the appropriate airway region and sample collection method to enrich detection of the transcript(s) of interest.