We examine the time until closure of Small Business Enterprises in Umbria, Italy between 2008 and 2013, and the factors that influence it. Earlier analysis, using Cox regression, considered failure (closure) from any cause. However, there are different reasons for inactivity: voluntary winding-up (1808 of 15184 firms in our data, 59.3% of the 3049 failures); bankruptcy (236, 7.7%); and closure without action by creditors or courts (1005, 33.0%). While the earlier analysis provides a valuable overall picture, it is also interesting to examine the separate causes, their rates of occurrence and which factors influence them separately. We do this using competing risks analyses, employing both of the regression methods that are prominent in the literature, based on cause-specific and sub-distribution hazard functions (Fine-Gray model). Furthermore, a proportional odds model was used to estimate cumulative incidences of failure by cause. Data included the firm's year of foundation, location, legal form and sector of activity. Financial indexes were constructed from annual balance sheets. The date and reason for closure were recorded if the firrm ceased activity. Findings included major differences between types of firm; for example, cooperatives had greatly increased hazards for winding-up (HR of 2.44 and 2.61 in the two approaches) but greatly reduced hazards for closure (0.48 and 0.45) compared to publicly traded companies. All-causes analysis averaged these strong effects into an insignicant one (1.05). Coefficients from the proportional odds model were similar to those from the Fine-Gray model, but have the advantage of interpretability.

Colorectal cancer has become one of the cancer types with high incidence rate all over the world. Various eorts have been carried out to nd a way to decrease the risk of cancer. Chemotherapy using 5-Fluorouracil (5-FU) is one of the common cancer treatments that is expected to drive the white blood cell (WBC) level into the normal level. This research investigates the factors inuencing the change of WBC level in cancer patients treated with 5-FU combined with physical treatment in the form of footsteps. By focusing on the change of WBC level, i.e. decreasing or increasing the WBC level as the response, probit regression was applied to the data measured from 28 cancer patients who have undergone 14 days of treatment. The probit regression found that age of the patient, average number of daily footsteps and the dose of 5-FU signcantly inuence the change of WBC. The regression is able to classify the case with a satisfactory results, i.e. 85.71% classication accuracy. This nding can be a guideline to better treat the colorectal cancer patient to reach a normal WBC.

In this paper, we present an analysis of more than 500K comments from open-sourcerepositories of software systems.Our aim is to empirically determine how developers interact with each otherunder certain psychological conditions generated by politeness, sentiment andemotion expressed within developers' comments.Developers involved in an open-source projects do not usually know each other; they mainly communicate through mailing lists, chat rooms, and tools such as issue tracking systems.The way in which they communicate affects the development process and the productivity of the people involved in the project.We evaluated politeness, sentiment and emotions of comments posted by developers and studied the communication flow to understand how they interacted in the presence of impolite and negative comments (and vice versa).Our analysis shows that when in presence of impolite or negative comments, the probability of the next comment being impolite or negative is 14% and 25%, respectively; anger however,has a probability of 40% of being followed by a further anger comment.The result could help managers take control the development phases of a system, since social aspects can seriously affect a developer's productivity. In a distributed environment this may have a particular resonance.

In practice, process capability indices (PCIs) are widely used in the field of quality control. The lifetime performance index ( C L ) is used to measure process potential and performance, where L is the lower specification limit. In this paper, we apply data transformation technology to construct a maximum likelihood estimator (MLE) of C L under the two-parameter Rayleigh distribution based on the progressively type II right censored sample. The MLE of C L is then utilized to develop a hypothesis testing procedure. Finally, we give the Monte Carlo power simulation to assess the behavior of the lifetime perform index.

In this paper we propose a numerical scheme to estimate the price of a barrier option in a general framework. More precisely, we extend a classical Sequential Monte Carlo approach, developed under the hypothesis of deterministic volatility, to Stochastic Volatility models, in order to improve the efficiency of Standard Monte Carlo techniques in the case of barrier options whose underlying approaches the barriers. The paper concludes with the application of our procedure to two case studies in a SABR model.

The paper investigates the use of a finite mixture model with an additional uniform density for outlier detection and robust estimation. The main contribution of this paper lies in the analysis of the properties of the improper component and the introduction of a modified EM algorithm which, beyond providing the maximum likelihood estimates of the mixture parameters, endogenously provides a numerical value for the density of the uniform distribution used for the improper component. The mixing proportion of outliers may be known or unknown. Applications to robust estimation and outlier detection will be discussed with particular attention to the normal mixture case.

To establish the computer assisted system of the visual acuity test, we propose a statistical modelling of the visual acuity measurement and its multiple test procedure. The psychometric functions for individual patients are produced by the logistic regression combined with the guessing rate. We adopt test statistics based on (i) psychometric functions (the Cochran-Mantel-Haenszel method) and (ii) psychophysical thresholds (the delta method). The multiple comparisons are performed by the step-down procedure with Ryan-Einot-Gabriel-Welsch (REGW) significance levels. To show the practical effectiveness of our system, we present a numerical example of four patient groups.

In this study, we propose a robust confidence interval for the mean of skewed populations. It is simple adjustment of the Student-t confidence interval based on the trimmed mean and the modified trimmed standard deviation. The proposed confidence interval is compared with existing confidence intervals in terms of coverage probability and average width for normal and skewed distributions with different parameter and skewness. The simulation study shows that the proposed robust confidence interval performs the best among the compared confidence intervals and it is better than the classical Student-t confidence interval. Also, proposed confidence interval has narrowest average width in all sample sizes. In addition to the simulation,some real-life examples have been considered for illustrating which support the findings of the simulation study. Consequently, we recommend confidence interval based on trimmed mean and the modified trimmed standard deviation to estimate the mean of positively skewed populations.

The assumption of carryover effects is unavoidable due to the very nature of crossover designs. Even in case of crossover design with washout period, the hypothesis of no carryover effect should be tested and established. On the other hand, this assumption makes the analysis difficult and potentially biased or inefficient in case of two treatment two period crossover design. For a reasonable estimation, experimenters are advocated to employ a two period three treatment crossover designs, or a three period two treatment crossover design. In this article, we present optional analyses of a uniform three period three treatment crossover design, consisting of a placebo and two active treatments. We develop a test for detecting presence of carryover effects which directs experimenter for a proper analysis of his crossover trial. We present ANOVA for each of the three possible carryover models, that both, single, or none of the active treatments has carryover effect, and illustrate through an example.

The reverse mortgage market has been expanding rapidly in developed economies in recent years. Reverse mortgages provide an alternative source of funding for retirement income and health care costs. Increase in life expectancies and decrease in the real income at retirement continue to worry the those who are retired or close to retirement. Therefore, financial products that help to alleviate the “risk of living longer” continue to be attractive among the retirees. Reverse mortgage contracts involve a range of risks from the insurer’s perspective. When the outstanding balance exceeds the housing value before the loan is settled, the insurer suffers an exposure to crossover risk induced by three risk factors: interest rates, house prices and mortality rates. We analyse the combined impact of these risks on the pricing and the risk profile of reverse mortgage loans in a stochastic interest-mortality-house pricing model. Our results show shows that pricing of reverse mortgages loans does not accurately assess the risks underwritten by reverse mortgages lenders and that failing to take into account mortality improvements substantially underestimates the longevity risk involved in reverse mortgage loans.