Humphreys's attenuated test of Spearman's hypothesis

Humphreys's test of Spearman's hypothesis (viz., that the size of the standardized black-white differences on various psychometric tests is positively related to the tests' loadings on g, the general intelligence factor) is methodologically weak. It is based on comparison of a fairly representative sample of the black population of U.S. school children with a highly selected sample of the white school population, representing the lowest 15 to 20% of whites in socio-economic status (SES). A fair test of the hypothesis requires that the black and white samples should not be selected on any g-correlated variable, such as SES. Selection attenuates and distorts the relationship between tests' g loadings and the magnitude of the standardized mean black-white differences on the tests. Other unorthodox conditions in Humphreys's study, such as performing factor analysis on the test-score means of various arbitrary demographic groups instead of on individual test scores inflates tests' g loadings and biases the test of Spearman's hypothesis by restriction of reliable variance in g loadings. Humphreys's study cannot be considered a proper replication of Jensen's examination of Spearman's hypothesis in 11 different studies comprising 74 different tests, which consistently bears out Spearman's hypothesis.     

Predicting young women's role preference for parenting and work

Young women's motivations for two sex-role options were predicted with scores describing perceived rewards/costs of parenting. Using a sequence of multiple regression analyses it was found that the reward-cost perceptions of parenting and work were predictors of the two motivational options. Individual rewards/costs of parenting and work items were better predictors than summed items. It was found that a preference for the career choice was produced by not viewing parenting as rewarding. The preference for parenting choice was influenced most by perceiving parenting as rewarding. The perceived cost and rewards of work were not predictors of a career choice. The items found to be the best predictors for either the parenting or career choice all dealt with perceptions of parenting. It was concluded that these parenting perceptions are the key elements for young women's role motivations.     

General mixture item response models with different item response structures: Exposition with an application to Likert scales

This article proposes a general mixture item response theory (IRT) framework that allows for classes of persons to differ with respect to the type of processes underlying the item responses. Through the use of mixture models, nonnested IRT models with different structures can be estimated for different classes, and class membership can be estimated for each person in the sample. If researchers are able to provide competing measurement models, this mixture IRT framework may help them deal with some violations of measurement invariance. To illustrate this approach, we consider a two-class mixture model, where a person’s responses to Likert-scale items containing a neutral middle category are either modeled using a generalized partial credit model, or through an IRTree model. In the first model, the middle category (“neither agree nor disagree”) is taken to be qualitatively similar to the other categories, and is taken to provide information about the person’s endorsement. In the second model, the middle category is taken to be qualitatively different and to reflect a nonresponse choice, which is modeled using an additional latent variable that captures a person’s willingness to respond. The mixture model is studied using simulation studies and is applied to an empirical example.     

Abortion, embryonic stem cell research, and waste

Can one consistently deny the permissibility of abortion while endorsing the killing of human embryos for the sake of stem cell research? The question is not trivial; for even if one accepts that abortion is prima facie wrong in all cases, there are significant differences with many of the embryos used for stem cell research from those involved in abortion—most prominently, many have been abandoned in vitro, and appear to have no reasonably likely meaningful future. On these grounds one might think to maintain a strong position against abortion but endorse killing human embryos for the sake of stem cell research and its promising benefits. I will argue, however, that these differences are not decisive. Thus, one who accepts a strong view against abortion is committed to the moral impermissibility of killing human embryos for the sake of stem cell research. I do not argue for the moral standing of either abortion or the killing of embryos for stem cell research; I only argue for the relation between the two. Thus the conclusion is relevant to those with a strong view in favor of the permissibility of killing embryos for the sake of research as much as for those who may strongly oppose abortion; neither can consider their position in isolation from the other.     

The Causal Exclusion Argument

Jaegwon Kim’s causal exclusion argument says that if all physical effects have sufficient physical causes, and no physical effects are caused twice over by distinct physical and mental causes, there cannot be any irreducible mental causes. In addition, Kim has argued that the nonreductive physicalist must give up completeness, and embrace the possibility of downward causation. This paper argues first that this extra argument relies on a principle of property individuation, which the nonreductive physicalist need not accept, and second that once we get clear on overdetermination, there is a way to reject the exclusion principle upon which the causal exclusion argument depends, but third that this should not lead to the belief that mental causation is easily accounted for in terms of counterfactual dependencies.