Biomedical subjects

Karen M Schmidt

Publications and source records attributed to Karen M Schmidt.

3 recordsLinked to original sources

PubMed2006

Using LinLog and FACETS to model item components in the LLTM.

The current study investigates the performance of two Rasch measurement programs and their parameter estimations on the linear logistic test model (LLTM; Fischer, 1973). These two programs, LinLog (Whitely & Nieh, 1981) and FACETS (Linacre, 2002), are used to investigate within-item complexity factors in a spatial memory measure tool. LinLog uses conditional maximum likelihood to estimate person and item parameters and is an LLTM specific program. FACETS is usually reserved for the many-facet Rasch model (MFRM; Linacre, 1989), however in the case of specifically designed within-item solution processes, a multifaceted approach makes good sense. It is possible to consider each dimension within the item as a separate facet, just as if there were multiple raters for each item. Simulations of 500 and 1000 persons expand the original data set (114 persons) to better examine each estimation technique. LinLog and FACETS analyses show strikingly similar results in both the simulation and original data conditions, indicating that the FACETS program produces accurate LLTM parameter estimates.

Humans↗

PubMed2005

Ethnic identification biases responses to the Padua Inventory for obsessive-compulsive disorder.

The authors report differential item functioning (DIF) between Black and White participants completing the 60-item Padua Inventory (PI) for obsessive-compulsive disorder (OCD). The authors use an Internet-generated sample that included 105 Blacks, 67 Hispanics, 582 Whites, and 136 additional participants reporting an OCD diagnosis. Factor analysis replicated prior work indicating the PI consists of four factors: contamination fears, checking behaviors, impaired control over thoughts, and fear of losing control over impulses. On the contamination subscale, nonclinical Black and Hispanic mean scores were as high as the OCD group. Comparing Blacks to Whites, the authors applied an item response theory, DIF-graded response model to each factor and found significant DIF on eight items, with biased items in each factor. Results suggest that extraneous factors contribute to racial differences on scores. Cultural practices and fear of being negatively stereotyped may contribute to item bias.

Adult↗

PubMed2005

Rasch analysis examining processing mechanisms of the object location memory test revised.

This study's objective was the construction and examination of the Object Location Memory Revised (OLM-R), an instrument designed to measure spatial memory. The OLM-R measured a participant's (N=111) ability to inspect a spatial array and recall image identities and positions after a distractor task. Rasch methodology and regression analyses were employed to explore the influence a priori design factors have on performance and item difficulty. Rasch analyses revealed that, while the OLM-R has a misfitting item, overall the instrument shows good measurement properties. Specific analyses examining complexity factors indicated that Object Manipulation (e.g., moving, replacing, or unchanging) and the Number of Items in an array were leading influences of OLM-R performance.

Adolescent↗