Statistical and methodological problems with concreteness and other semantic variables: A list memory experiment case study

The purpose of this article is to highlight problems with a range of semantic psycholinguistic variables (concreteness, imageability, individual modality norms, and emotional valence) and to provide a way of avoiding these problems. Focusing on concreteness, I show that for a large class of words in the Brysbaert, Warriner, and Kuperman (Behavior Research Methods 46: 904–911, 2013) concreteness norms, the mean concreteness values do not reflect the judgments that actual participants made. This problem applies to nearly every word in the middle of the concreteness scale. Using list memory experiments as a case study, I show that many of the “abstract” stimuli in concreteness experiments are not unequivocally abstract. Instead, they are simply those words about which participants tend to disagree. I report three replications of list memory experiments in which the contrast between concrete and abstract stimuli was maximized, so that the mean concreteness values were accurate reflections of participants’ judgments. The first two experiments did not produce a concreteness effect. After I introduced an additional control, the third experiment did produce a concreteness effect. The article closes with a discussion of the implications of these results, as well as a consideration of variables other than concreteness. The sensorimotor experience variables (imageability and individual modality norms) show the same distribution as concreteness. The distribution of emotional valence scores is healthier, but variability in ratings takes on a special significance for this measure because of how the scale is constructed. I recommend that researchers using these variables keep the standard deviations of the ratings of their stimuli as low as possible

Permutation sampling in Path Integral Monte Carlo

A simple algorithm is described to sample permutations of identical particles in Path Integral Monte Carlo (PIMC) simulations of continuum many-body systems. The sampling strategy illustrated here is fairly general, and can be easily incorporated in any PIMC implementation based on the staging algorithm. Although it is similar in spirit to an existing prescription, it differs from it in some key aspects. It allows one to sample permutations efficiently, even if long paths (e.g., hundreds, or thousands of slices) are needed. We illustrate its effectiveness by presenting results of a PIMC calculation of thermodynamic properties of superfluid Helium-four, in which a very simple approximation for the high-temperature density matrix was utilized

Blame Canada (and the Rest of the World): The Twenty-Year War on Imported Prescription Drugs

Rising budget deficits and sticker shock over the new Medicare drug benefit have put the issue of prescription drug costs back into the spotlight. The growth in the cost of prescription drugs continues to represent a staggering burden for taxpayer-funded health care programs, even while costs of non-drug health care services have slowed or even decreased. Among the many proposals for cutting prescription drug costs, drug importation is unique. Although bipartisan support for drug importation has existed in Congress for over five years, the federal government continues to maintain that a system of safe and effective drug importation is impossible. This paper provides a comprehensive analysis of importation law and legislation as it has evolved over the past twenty years. The paper tells the story of drug importation’s checkered legislative history, beginning with adulterated Guatemalan birth-control pills and culminating with an unprecedented trade embargo by Canadian officials, which may soon prohibit all drug sales to customers in the United States. Additionally, the paper looks at the case law that has arisen from drug importation and describes how consumers and state governments are now turning to the judicial branch to force the federal government to ensure that imported prescription drugs are safe and effective for consumers