The Infinitesimal Jackknife and Moment Structure Analysis Using Higher Order Moments.

Mean corrected higher order sample moments are asymptotically normally distributed. It is shown that both in the literature and popular software the estimates of their asymptotic covariance matrices are incorrect. An introduction to the infinitesimal jackknife is given and it is shown how to use it to correctly estimate the asymptotic covariance matrices of higher order sample moments.

Continuous orthogonal complement functions and distribution-free goodness of fit tests in moment structure analysis.

It is shown that for any full column rank matrix X 0 with more rows than columns there is a neighborhood [Formula: see text] of X 0 and a continuous function f on [Formula: see text] such that f(X) is an orthogonal complement of X for all X in [Formula: see text]. This is used to derive a distribution free goodness of fit test for covariance structure analysis. This test was proposed some time ago and is extensively used.

The nonsingularity of γ in covariance structure analysis of nonnormal data.

Covariance structure analysis of nonnormal data is important because in practice all data are nonnormal. When applying covariance structure analysis to nonnormal data, it is generally assumed that the asymptotic covariance matrix Γ for the nonredundant terms in the sample covariance matrix S is nonsingular. It is shown this need not be the case, which raises a question of how restrictive this assumption may be and how difficult it may be to verify it.

A cluster-based factor rotation.

A new oblique factor rotation method is proposed, the aim of which is to identify a simple and well-clustered structure in a factor loading matrix. A criterion consisting of the complexity of a factor loading matrix and a between-cluster dissimilarity is optimized using the gradient projection algorithm and the k-means algorithm. It is shown that if there is an oblique rotation of an initial loading matrix that has a perfect simple structure, then the proposed method with Kaiser's normalization will produce the perfect simple structure.

Primary androgen deprivation (AD) followed by active surveillance (AS) for newly diagnosed prostate cancer (PC): A retrospective study.

Background: Active surveillance (AS) is only recommended for Low-Risk prostate cancer (PC) with <34% biopsies positive. Studies describing the long-term outcome of men treated with androgen deprivation (AD) followed by AS are sparse.

Materials And Methods: One hundred two men were treated with 12 months of AD in a medical oncology clinic specializing in PC between 1998 and 2007 and were followed for a median of 7.

Exploratory Bi-factor Analysis: The Oblique Case.

Bi-factor analysis is a form of confirmatory factor analysis originally introduced by Holzinger and Swineford (Psychometrika 47:41-54, 1937). The bi-factor model has a general factor, a number of group factors, and an explicit bi-factor structure. Jennrich and Bentler (Psychometrika 76:537-549, 2011) introduced an exploratory form of bi-factor analysis that does not require one to provide an explicit bi-factor structure a priori.

Exploratory Bi-factor Analysis.

Bi-factor analysis is a form of confirmatory factor analysis originally introduced by Holzinger. The bi-factor model has a general factor and a number of group factors. The purpose of this paper is to introduce an exploratory form of bi-factor analysis.

Primary intermittent androgen deprivation as initial therapy for men with newly diagnosed prostate cancer.

Background: The purpose of this study was to describe the long-term incidence of cancer progression and mortality in men with localized prostate cancer treated with primary androgen deprivation (AD).

Methods: A retrospective chart review, from a medical oncology practice specializing in prostate cancer, was conducted of 73 men eligible for surgery or radiation treated with induction AD. Entry criteria consisted of a minimum of 9 months of induction AD, treatment initiation before 1999, clinical stage < T3, and outcome defined as the incidence of delayed local therapy, cancer progression, cancer mortality, and mortality from other causes.

Prostate-cancer-specific survival and clinical progression-free survival in men with prostate cancer treated intermittently with testosterone-inactivating pharmaceuticals.

Objectives: More than 85% of men with prostate cancer die of other causes. An effective method is needed to distinguish fatal forms of prostate cancer from benign variants.

Methods: We performed a retrospective chart review from a medical oncology practice specializing in prostate cancer.

Intermittent use of testosterone inactivating pharmaceuticals using finasteride prolongs the time off period.

Purpose: Men with prostate cancer treated intermittently with TIP benefit from improved quality of life when TOP with recovered testosterone is prolonged. We examined factors influencing the duration of TOP.

Materials And Methods: We retrospectively reviewed the charts of 101 men treated with intermittent TIP in a 9-year period.

The predictive role of blood glucose for mortality in subjects with cardiovascular disease.

Using the Framingham Heart Study data (United States, 1948-1978), the authors examined the association of blood glucose with 2-year all-cause, cardiovascular, and noncardiovascular mortality in subjects with documented cardiovascular disease. After adjustment for systolic blood pressure, cholesterol, body mass index, cigarette smoking, and use of antihypertensive agents, they found that glucose was a strong, independent predictor of mortality. However, the relations for men and women were qualitatively different.

Independent component analysis as a rotation method: a very different solution to Thurstone's box problem.

In this paper we consider the well-known Thurstone box problem in exploratory factor analysis. Initial loadings and components are extracted using principal component analysis. Rotating the components towards independence rather than rotating the loadings towards simplicity allows one to accurately recover the dimensions of each box and also produce simple loadings.

Blood glucose: a strong risk factor for mortality in nondiabetic patients with cardiovascular disease.

Background: The prognostic significance of blood glucose (BG) for nondiabetic patients in a stable chronic phase of cardiovascular disease (CVD) has been sparsely investigated, especially for glucose within the normal range. In particular, it is unknown if for these patients there is a graded relation of mortality to glucose or if there is a lower threshold.

Methods: We used the Framingham Heart Study 30-year data to determine 2-year all-cause, cardiovascular mortality (CVM), and non-CVM risk adjusted for age, sex, and typical cardiovascular risk factors (systolic blood pressure, total cholesterol, body mass index, cigarette smoking, and use of antihypertensive drugs) by levels of random whole BG for non-glucose-intolerant subjects (glucose intolerance includes diabetes mellitus) with existing CVD.

Long-term outcome for men with androgen independent prostate cancer treated with ketoconazole and hydrocortisone.

Purpose: The combination of high dose ketoconazole and hydrocortisone (HDK) is active against androgen independent prostate cancer (AIPC). Median response times with HDK tend to be brief but a significant minority of AIPC patients benefit with extended responses. Well characterized response and survival information, especially in the cohort of patients who experience these longer, more durable, responses has not been previously reported.

beta-Cell function: a key pathological determinant in polycystic ovary syndrome.

We report data from 60 patients with polycystic ovary syndrome (PCOS) who had undergone assessment of insulin resistance, pancreatic beta-cell function, obesity, and androgen levels to elucidate the complex relationships among these traits. Homeostasis model assessment was used to quantify insulin resistance and beta-cell function. A reference population was derived from the National Health and Nutrition Examination Study (NHANES III, 1988-1994).

Modified citrus pectin (MCP) increases the prostate-specific antigen doubling time in men with prostate cancer: a phase II pilot study.

This trial investigated the tolerability and effect of modified citrus pectin (Pecta-Sol) in 13 men with prostate cancer and biochemical prostate-specific antigen (PSA) failure after localized treatment, that is, radical prostatectomy, radiation, or cryosurgery. A total of 13 men were evaluated for tolerability and 10 for efficacy. Changes in the prostate-specific antigen doubling time (PSADT) of the 10 men were the primary end point in the study.

Relative impact of insulin resistance and obesity on cardiovascular risk factors in polycystic ovary syndrome.

Polycystic ovary syndrome (PCOS) affects 5% to 7% of women of reproductive age. Insulin resistance and obesity are components of this important syndrome that may contribute to excess cardiovascular risk. We analyzed data from 69 patients with PCOS who had undergone quantitative assessment of insulin sensitivity, blood pressure, lipid profiles, and androgen levels to determine the impact of insulin resistance and obesity on parameters of cardiovascular risk.

Using splines to detect changes in PSA doubling times.

Background: PSA doubling time (PSADT) can predict the likelihood of clinical progression in patients with biochemical relapse after surgery or radiation for prostate cancer. Changes in PSA doubling time in response to therapy may be of clinical or investigational significance. How does one estimate PSADT before and after the initiation of therapy and determine if any change is statistically significant or simply the result of random variation? These are the type of questions addressed.

Systolic blood pressure and mortality.

Background: The current systolic blood-pressure threshold for hypertension treatment is 140 mm Hg for all adults. WHO and the International Society of Hypertension have proposed that normal pressure be lower than 130 mm Hg, with an optimum pressure of less than 120 mm Hg. These recommendations are based largely on the assumption that cardiovascular and overall mortality depend in a strictly increasing manner on systolic blood pressure.

Unbalanced repeated-measures models with structured covariance matrices.

The question of how to analyze unbalanced or incomplete repeated-measures data is a common problem facing analysts. We address this problem through maximum likelihood analysis using a general linear model for expected responses and arbitrary structural models for the within-subject covariances. Models that can be fit include standard univariate and multivariate models with incomplete data, random-effects models, and models with time-series and factor-analytic error structures.

Some practical problems arising from use of the gamma multihit model for risk estimation.

The Scientific Committee of the Food Safety Council recently recommended use of the gamma multihit model for risk assessment. Some practical problems arising from the use of this model are presented. In some instances the model produces what appear to be unreasonably high "safe dose" estimates.