Controlling for Unobserved Confounds in Classification Using Correlational Constraints

As statistical classifiers become integrated into real-world applications, it is important to consider not only their accuracy but also their robustness to changes in the data distribution. In this paper, we consider the case where there is an unobserved confounding variable $z$ that influences both the features $\mathbf{x}$ and the class variable $y$. When the influence of $z$ changes from training to testing data, we find that the classifier accuracy can degrade rapidly. In our approach, we assume that we can predict the value of $z$ at training time with some error. The prediction for $z$ is then fed to Pearl's back-door adjustment to build our model. Because of the attenuation bias caused by measurement error in $z$, standard approaches to controlling for $z$ are ineffective. In response, we propose a method to properly control for the influence of $z$ by first estimating its relationship with the class variable $y$, then updating predictions for $z$ to match that estimated relationship. By adjusting the influence of $z$, we show that we can build a model that exceeds competing baselines on accuracy as well as on robustness over a range of confounding relationships.Comment: 9 page

Continuum Beliefs and Schizophrenia Stigma: Correlational and Experimental Evidence

Recent correlational research has indicated that belief in a continuum of psychiatric problems is related to decreased psychiatric stigma. These findings have generated enthusiasm to conceive antistigma programming centered on encouraging embrace of continuum beliefs. However, the extant correlational literature does little to support the prospects of manipulation of continuum beliefs. Moreover, several factors converge to suggest that an experimental manipulation of continuum beliefs cannot easily be achieved. Volunteers in an online study read a detailed description of a young man with schizophrenia and were then randomized to read either (a) a summary of research attesting to a continuum view of schizophrenia, (b) a summary of research attesting to a categorical view of schizophrenia, or (c) no additional material. Respondents also completed self-report measures of the strength of their endorsement of continuum and categorical views of schizophrenia. Consistent with published correlational findings, greater endorsement of the continuum view was related to less desire for social distance, lesser endorsement of the unpredictability stereotype, and marginally less fear. On the other hand, there was no evidence that experimental manipulation of continuum beliefs affected stigma. The current findings are discussed in the context of other recent continuum-based antistigma interventions. Additional work is needed to more fully evaluate the prospects of such an approach

Non-rigid Shell Model and Correlational Mechanism of the Local Pairing

The Hartree-Fock states of the many-electron atomic system can be unstable with respect to a static or dynamic shift of the electron shells. An appropriate non-rigid shell model for atomic clusters is developed. It permits to formulate a convenient approach to the semiempirical description of the different correlation effects and to reveal some new effects.Comment: 3 pages, 2 ".gif" figures, LaTeX; will be published in Physica C in Materials of Int.Conf. HTSC-V. (1997, Beijing, China

Correlational analysis between joint-level kinetics of countermovement jumps and weightlifting derivatives

The purpose of this study was to investigate the mechanical similarity between net joint moments (NJM) of the countermovement jump (CMJ) and the hang power clean (HPC) and jump shrug (JS). Twelve male Lacrosse players performed three maximal effort CMJs and three repetitions of the HPC and JS at 30%, 50%, and 70% of their HPC one repetition maximum (1-RM). Ground reaction forces and motion capture data were used to calculate the NJM of the hip, knee, and ankle joints during each exercise. Statistical comparison of the peak NJM indicated that NJM during the HPC and JS across all loads were equal to or greater than the NJM during the CMJ (all p < 0.025). In addition, correlation analyses indicated that CMJ hip NJM were associated (all p < 0.025) with HPC hip NJM at 30% and 70% (r = 0.611-0.822) and JS hip NJM at 50% and 70% (r = 0.674-0.739), whereas CMJ knee NJM were associated with HPC knee NJM at 70% (r = 0.638) and JS knee NJM at 50% and 70% (r = 0.664-0.732). Further, CMJ ankle NJM were associated with HPC ankle NJM at 30% and 50% (r = 0.615-0.697) and JS ankle NJM at 30%, 50%, and 70% (r = 0.735-0.824). Lastly, knee and ankle NJM during the JS were greater than during the HPC at 30% and 50% of 1-RM (all p < 0.017). The degree of mechanical similarity between the CMJ and the HPC and JS is dependent on the respective load and joint. [Abstract copyright: © Journal of Sports Science and Medicine.

An Examination of Student Performance in Pre-Requisite Coursework and Upper Division Nursing Coursework

Admission and retention of qualified nursing students are essential in meeting the demands of a rapidly changing health care environment and nursing shortage. The purpose of this exploratory correlational study was to determine the relationship between student performance in quantitative pre-requisite coursework and student performance in upper division nursing coursework in order to identify students at-risk for attrition. A series of descriptive and correlational analyses were conducted using pre-existing institutional data. A moderate relationship existed among the chemistry II and first-year upper division nursing courses (r = .21 to r = .40). These results suggest that prerequisite chemistry course performance could be a reliable predictor of academic success