Conference contrasts

Simple Effects, Simple Contrasts, and Main Effect Contrasts

Simple Effects Following a significant interaction, follow-up tests are usually needed to explore the exact nature of the interaction. Simple effects (sometimes called simple main effects) are differences among particular cell means within the design. More precisely, a simple effect is the effect of one independent variable within one level of a second independent variable. In our hypothetical ...

Projected likelihood contrasts

This paper develops a test for homogeneity in finite mixture models where the mixing proportions are known a priori (taken to be 0.5) and a common nuisance parameter is present. Statistical tests based on the notion of Projected Likelihood Contrasts (PLC) are considered. The PLC is a slight modification of the usual likelihood ratio statistic or the Wilk’s Λ and is similar in spirit to the Rao’...

Phonation Contrasts across Languages

This study compares the phonetics of phonation categories within and across four languages: Gujarati (modal, breathy), White Hmong (modal, breathy, creaky), Jalapa Mazatec (modal, breathy, creaky), and Southern Yi (tense, lax). In addition to acoustic measures in all four languages, electroglottographic measures were also compared for Gujarati, Hmong, and Yi. Several measures distinguished phon...

Contrasts in neuronal aggregates

he protein aggregates of various neuro-degenerative diseases are not created equal. So say Matsumoto et al. (page 75), who find that the aggregates of familial amyo-trophic lateral sclerosis (fALS) are unusually porous compared to those of Huntington's disease (HD). Both diseases are associated with the neuronal aggregation of a mutant protein in affected individuals. For fALS, the mutant prote...

Contrasts and Classical Inference