What does differential item functioning?
In brief, differential item functioning (DIF) occurs when groups (such as defined by gender, ethnicity, age, or education) have different probabilities of endorsing a given item on a multi-item scale after controlling for overall scale scores.
What is differential test functioning?
Differential test functioning (DTF) is when the total score functions differently across groups such that the final scores do not represent the same measurement across the population of test-takers (Raju et al. 1995).
What are dif studies?
DIF studies demonstrate in vivo deposits of antibodies and other immunoreactants, such as complement. DIF tests usually demonstrate IgG (70-90% of patients) and complement C3 deposition (90-100% of patients) in a linear band at the dermal-epidermal junction.
What is non uniform dif?
Non-uniform DIF ICCs. This will show you which items have an interaction between item difficulty, group membership and ability. If you see an item for which the item difficulty is noticeably different for high and low performers in a group, then Table 30.1 will report the statistical significance of the difference.
How do you test for dif?
DIF analysis is conducted by comparing a reference group (typically the majority, or normative, group) with a focal group (typically the minority, or disadvantaged, group). For example, a study probing for bias against women would use men as the reference group and women as the focal group.
What is Item bias?
Item bias is generally defined as conditional dependence; within the framework of item response theory the general definition implies that the item characteristic curves of two groups do not coincide. For detecting biased items, statistical tests and indices based on item response theory have been proposed.
What is a dif biopsy?
It is also called the direct immune fluorescent test or primary immunofluorescence. DIF involves the application of antibody–fluorophore conjugate molecules to samples of patient tissue obtained from biopsies. These antibody–fluorophore conjugates target abnormal depositions of proteins in the patient’s tissue.
What is pemphigus vulgaris?
What is pemphigus vulgaris? Pemphigus is a rare group of autoimmune diseases. It causes blisters on the skin and mucous membranes throughout the body. It can affect the mouth, nose, throat, eyes, and genitals. Pemphigus vulgaris is the most common type of pemphigus.
What is item response theory used for?
Item response theory (IRT) was first proposed in the field of psychometrics for the purpose of ability assessment. It is widely used in education to calibrate and evaluate items in tests, questionnaires, and other instruments and to score subjects on their abilities, attitudes, or other latent traits.
What is dif in psychometrics?
Differential item functioning (DIF) is the preferred psychometric term for what is otherwise known as item bias. An item displays DIF when test takers possessing the same amount of an ability or trait, but belonging to different subgroups, do not share the same likelihood of correctly answering the item.
What is differential validity?
Differential validity refers to differences between subgroups in the validity coefficients (i.e., correlations between cognitive ability tests and job performance) for a cognitive ability test.
What is Item bias on a test?
