Why Write Statistical Software? The Case of Robust Statistical Methods

Robust statistical methods are designed to work well when classical assumptions, typically normality and/or the lack of outliers, are violated. Almost everyone agrees on the value of robust statistical procedures. Nonetheless, after more than 40 years and thousands of papers, few robust methods were available in standard statistical software packages until very recently. This paper argues that one of the primary reasons for the lack of robust statistical methods in standard statistical software packages is the fact that few developers of statistical methods are willing to write user-friendly and readable software for the methods they develop, regardless of the usefulness of the method. Recent changes in academic statistics make it highly desirable for all developers of statistical methods to provide usable code for their statistical methods

Nonparametric Control Chart for the Range

The method comprises establishing the number of subsets of a dataset that have a range of the difference between any two datapoints within the dataset, and computing a control chart for the range based thereon. In another aspect, a software program for accomplishing the method of the present invention is provided. The method of the invention allows monitoring variability of a product being produced by a particular piece of machinery, of a process conducted by the machinery, or of a product stream generated thereby, accurately detecting changes in variability in real time. The true distribution of the data is reflected, and the desired result is achieved without requiring an inordinate number of computations

Nonparametric Control Chart for the Range

A method is provided for detecting or predicting an undesired deviation in variability of at least one parameter being monitored, wherein the variation in the parameter is incrementally recorded. The method comprises establishing the number of subsets of a dataset that have a range of the difference between any two datapoints within the dataset, and computing a control chart for the range based thereon. The method accurately detects changes in variability in real time. The true distribution of the data is reflected, and the desired result is achieved without requiring an inordinate number of computations

Computing the exact value of the least median of squares estimate in multiple linear regression

1 online resource (PDF, 15 pages

High Breakdown Estimation of Nonlinear Regression Parameters

1 online resource (PDF, 36 pages

Breakdown in Nonlinear Regression

1 online resource (PDF, 21 pages

Differential gene expression associated with postnatal equine articular cartilage maturation

<p>Abstract</p> <p>Background</p> <p>Articular cartilage undergoes an important maturation process from neonate to adult that is reflected by alterations in matrix protein organization and increased heterogeneity of chondrocyte morphology. In the horse, these changes are influenced by exercise during the first five months of postnatal life. Transcriptional profiling was used to evaluate changes in articular chondrocyte gene expression during postnatal growth and development.</p> <p>Methods</p> <p>Total RNA was isolated from the articular cartilage of neonatal (0–10 days) and adult (4–5 years) horses, subjected to one round of linear RNA amplification, and then applied to a 9,367-element equine-specific cDNA microarray. Comparisons were made with a dye-swap experimental design. Microarray results for selected genes (COL2A1, COMP, P4HA1, TGFB1, TGFBR3, TNC) were validated by quantitative polymerase chain reaction (qPCR).</p> <p>Results</p> <p>Fifty-six probe sets, which represent 45 gene products, were up-regulated (p < 0.01) in chondrocytes of neonatal articular cartilage relative to chondrocytes of adult articular cartilage. Conversely, 586 probe sets, which represent 499 gene products, were up-regulated (p < 0.01) in chondrocytes of adult articular cartilage relative to chondrocytes of neonatal articular cartilage. Collagens, matrix-modifying enzymes, and provisional matrix non-collagenous proteins were expressed at higher levels in the articular cartilage of newborn foals. Those genes with increased mRNA abundance in adult chondrocytes included leucine-rich small proteoglycans, matrix assembly, and cartilage maintenance proteins.</p> <p>Conclusion</p> <p>Differential expression of genes encoding matrix proteins and matrix-modifying enzymes between neonates and adults reflect a cellular maturation process in articular chondrocytes. Up-regulated transcripts in neonatal cartilage are consistent with growth and expansion of the articular surface. Expression patterns in mature articular cartilage indicate a transition from growth to homeostasis, and tissue function related to withstanding shear and weight-bearing stresses.</p

Analytic Approaches for Causal Inference with Complex Multi-Component Interventions

Estimating the causal effects of complex, multi-component health interventions is a task with many challenges in measurement and methodology. This presentation profiles the methods being used as part of the PCORI-funded Project Achieve, a national study to estimate the comparative effectiveness of heterogeneous care transition programs designed to help hospitalized patients and their caregivers navigate care delivery systems effectively and return back to the community with optimal health and wellbeing