poLCA: An R Package for Polytomous Variable Latent Class Analysis

poLCA is a software package for the estimation of latent class and latent class regression models for polytomous outcome variables, implemented in the R statistical computing environment. Both models can be called using a single simple command line. The basic latent class model is a finite mixture model in which the component distributions are assumed to be multi-way cross-classification tables with all variables mutually independent. The latent class regression model further enables the researcher to estimate the effects of covariates on predicting latent class membership. poLCA uses expectation-maximization and Newton-Raphson algorithms to find maximum likelihood estimates of the model parameters

An Accounting Liability Heuristic

This article traces the thought processes involved in understanding and managing accountants’ legal liability which is sometimes broadly called “professional malpractice.” The cumulative nature of potential liability is demonstrated.  The various legal theories of liability are discussed along with the most prominent potential affirmative defenses against liability. Unique to this paper is the decision heuristic providing a framework for assessing potential accountants’ legal liability.  This discussion is useful for both student and practitioner

The Still Secret Ballot: The Limited Privacy Cost of Transparent Election Results

After an election, should election officials release an electronic record of each ballot? The release of such cast vote records could bolster the legitimacy of the certified result. But it may also facilitate vote revelation, where an analyst unravels the secret ballot by uniquely linking vote choices on the anonymous ballot to the voter's name and address in the public voter file. We provide the first empirical study of the extent of vote revelation under several possible election-reporting regimes, ranging from precinct-level results to the individual ballot records known as cast vote records. Using Maricopa County, Arizona, as a case study, we find that cast vote records could reveal less than 0.2% of any voters' choices in the 2020 general election. Perhaps counterintuitively, releasing cast vote records coded by precinct and vote method are no more revelatory than releasing aggregate vote tallies for each precinct and vote method. We conclude that cast vote records are sufficiently privacy-protecting, and suggest how the privacy violations that do remain could be reduced.Comment: Initial draft, 42 pages, 6 figures, 2 table

Scaling Roll Call Votes with wnominate in R

This paper presents a software package designed to estimate Poole and Rosenthal W-NOMINATE scores in R. The package uses a logistic regression model to analyze political choice data, usually (though not exclusively) from a legislative setting. In contrast to other scaling methods, W-NOMINATE explicitly assumes probabilistic voting based on a spatial utility function, where the parameters of the utility function and the spatial coordinates of the legislators and the votes can all be estimated on the basis of observed voting behavior. Building on software written by Poole in Fortran, the new wnominate package in R facilitates easier data input and manipulation, generates bootstrapped standard errors, and includes a new suite of graphics functions to display the results. We demonstrate the functionality of this package by conducting a natural experiment using roll calls -- an experiment which is greatly simplified by the data manipulation capabilities of the wnominate package in R

Motor Output Structure in Targeted Aiming: A Mechanistic Model

Studies using a variety of experimental tasks have established that when humans repeatedly produce an action, fluctuations in action output are highest at the lowest frequencies and fluctuation magnitude (power) systematically declines as frequency increases. Such time series structure is termed pink noise. However, the appearance of pink noise seems to be limited to tasks where action is executed in the absence of task-related feedback. A few studies have demonstrated that when action was executed in the presence of task-related feedback, power was evenly distributed across all spectral frequencies—i.e., white noise was revealed. Here, participants produced cyclical aiming movements under visual feedback conditions and we sought to determine whether variations of both the movement amplitude requirement (A) and the target width (W)—in the form of the index of difficulty [ID = log2(2A/W)]—would predict the structure of movement amplitude (MA) time series. There were five ID levels, and there was a small-, medium-, and large-scale version of each ID: The A and W values doubled with each increment in scale level. Given that increases in ID are known to induce increased reliance on the available visual feedback, we predicted an ID-induced shift in MA time series structure from pink to white noise, with no change in MA structure across scale levels.https://engagedscholarship.csuohio.edu/u_poster_2014/1020/thumbnail.jp

Bioresorbable Polylactide Interbody Implants in an Ovine Anterior Cervical Discectomy and Fusion Model: Three-Year Results

Study Design. In vivo study of anterior discectomy and fusion using a bioresorbable 70:30 poly(l-lactide-co-d,l-lactide) interbody implant in an ovine model. Objective. To evaluate the efficacy of the polylactide implant to function as an interbody fusion device, and to assess the tissue reaction to the material during the resorption process. Summary of Background Data. The use of polylactide as a cervical interbody implant has several potential advantages when compared with traditional materials. Having an elastic modulus very similar to bone minimizes the potential for stress shielding, and as the material resorbs additional loading is transferred to the developing fusion mass. Although preclinical and clinical studies have demonstrated the suitability of polylactide implants for lumbar interbody fusion, detailed information on cervical anterior cervical discectomy and fusion (ACDF) with polylactide devices is desirable. Methods. Single level ACDF was performed in 8 skeletally mature ewes. Bioresorbable 70:30 poly (l-lactide-co-d,l-lactide) interbody implants packed with autograft were used with single-level metallic plates. Radiographs were made every 3 months up to 1 year, and yearly thereafter. The animals were killed at 6 months (3 animals), 12 months (3 animals), and 36 months (2 animals). In addition to the serial plain radiographs, the specimens were evaluated by nondestructive biomechanical testing and undecalcified histologic analysis. Results. The bioresorbable polylactide implants were effective in achieving interbody fusion. The 6-month animals appeared fused radiographically and biomechanically, whereas histologic sections demonstrated partial fusion (in 3 of 3 animals). Radiographic fusion was confirmed histologically and biomechanically at 12 months (3 of 3 animals) and 36 months (2 of 2 animals). A mild chronic inflammatory response to the resorbing polylactide implant was observed at both 6 months and 12 months. At 36 months, the operative levels were solidly fused and the implants were completely resorbed. No adverse tissue response was observed in any animal at any time period. Conclusion. Interbody fusion was achieved using bioresorbable polylactide implants, with no evidence of implant collapse, extrusion, or adverse tissue response to the material. The use of polylactide as a cervical interbody device appears both safe and effective based on these ACDF animal model results