**Commenced**in January 2007

**Frequency:**Monthly

**Edition:**International

**Paper Count:**19

# Search results for: censored

##### 19 Retail Strategy to Reduce Waste Keeping High Profit Utilizing Taylor's Law in Point-of-Sales Data

**Authors:**
Gen Sakoda,
Hideki Takayasu,
Misako Takayasu

**Abstract:**

Waste reduction is a fundamental problem for sustainability. Methods for waste reduction with point-of-sales (POS) data are proposed, utilizing the knowledge of a recent econophysics study on a statistical property of POS data. Concretely, the non-stationary time series analysis method based on the Particle Filter is developed, which considers abnormal fluctuation scaling known as Taylor's law. This method is extended for handling incomplete sales data because of stock-outs by introducing maximum likelihood estimation for censored data. The way for optimal stock determination with pricing the cost of waste reduction is also proposed. This study focuses on the examination of the methods for large sales numbers where Taylor's law is obvious. Numerical analysis using aggregated POS data shows the effectiveness of the methods to reduce food waste maintaining a high profit for large sales numbers. Moreover, the way of pricing the cost of waste reduction reveals that a small profit loss realizes substantial waste reduction, especially in the case that the proportionality constant of Taylor’s law is small. Specifically, around 1% profit loss realizes half disposal at =0.12, which is the actual value of processed food items used in this research. The methods provide practical and effective solutions for waste reduction keeping a high profit, especially with large sales numbers.

**Keywords:**
Time Series Analysis,
Food Waste Reduction,
Sustainable Development Goals,
particle filter,
Taylor's law,
point of sales

##### 18 A Study on the Waiting Time for the First Employment of Arts Graduates in Sri Lanka

**Authors:**
Imali T. Jayamanne,
K. P. Asoka Ramanayake

**Abstract:**

Transition from tertiary level education to employment is one of the challenges that many fresh university graduates face after graduation. The transition period or the waiting time to obtain the first employment varies with the socio-economic factors and the general characteristics of a graduate. Compared to other fields of study, Arts graduates in Sri Lanka, have to wait a long time to find their first employment. The objective of this study is to identify the determinants of the transition from higher education to employment of these graduates using survival models. The study is based on a survey that was conducted in the year 2016 on a stratified random sample of Arts graduates from Sri Lankan universities who had graduated in 2012. Among the 469 responses, 36 (8%) waiting times were interval censored and 13 (3%) were right censored. Waiting time for the first employment varied between zero to 51 months. Initially, the log-rank and the Gehan-Wilcoxon tests were performed to identify the significant factors. Gender, ethnicity, GCE Advanced level English grade, civil status, university, class received, degree type, sector of first employment, type of first employment and the educational qualifications required for the first employment were significant at 10%. The Cox proportional hazards model was fitted to model the waiting time for first employment with these significant factors. All factors, except ethnicity and type of employment were significant at 5%. However, since the proportional hazard assumption was violated, the lognormal Accelerated failure time (AFT) model was fitted to model the waiting time for the first employment. The same factors were significant in the AFT model as in Cox proportional model.

**Keywords:**
Survey Design,
waiting time,
AFT model,
first employment,
proportional hazard

##### 17 A Combined Approach of a Sequential Life Testing and an Accelerated Life Testing Applied to a Low-Alloy High Strength Steel Component

**Authors:**
D. I. De Souza,
D. R. Fonseca,
G. P. Azevedo

**Abstract:**

Sometimes the amount of time available for testing could be considerably less than the expected lifetime of the component. To overcome such a problem, there is the accelerated life-testing alternative aimed at forcing components to fail by testing them at much higher-than-intended application conditions. These models are known as acceleration models. One possible way to translate test results obtained under accelerated conditions to normal using conditions could be through the application of the “Maxwell Distribution Law.” In this paper we will apply a combined approach of a sequential life testing and an accelerated life testing to a low alloy high-strength steel component used in the construction of overpasses in Brazil. The underlying sampling distribution will be three-parameter Inverse Weibull model. To estimate the three parameters of the Inverse Weibull model we will use a maximum likelihood approach for censored failure data. We will be assuming a linear acceleration condition. To evaluate the accuracy (significance) of the parameter values obtained under normal conditions for the underlying Inverse Weibull model we will apply to the expected normal failure times a sequential life testing using a truncation mechanism. An example will illustrate the application of this procedure.

**Keywords:**
Hypothesis testing,
accelerated life testing,
Sequential Life Testing,
Maximum Likelihood Approach,
Underlying Three-Parameter Weibull Model

##### 16 Survival Model for Partly Interval-Censored Data with Application to Anti D in Rhesus D Negative Studies

**Authors:**
F. A. M. Elfaki,
Amar Abobakar,
M. Azram,
M. Usman

**Abstract:**

This paper discusses regression analysis of partly interval-censored failure time data, which is occur in many fields including demographical, epidemiological, financial, medical and sociological studies. For the problem, we focus on the situation where the survival time of interest can be described by the additive hazards model in the present of partly interval-censored. A major advantage of the approach is its simplicity and it can be easily implemented by using R software. Simulation studies are conducted which indicate that the approach performs well for practical situations and comparable to the existing methods. The methodology is applied to a set of partly interval-censored failure time data arising from anti D in Rhesus D negative studies.

**Keywords:**
EM algorithm,
Anti D in Rhesus D negative,
Cox’s model

##### 15 Inferences on Compound Rayleigh Parameters with Progressively Type-II Censored Samples

**Authors:**
Abdullah Y. Al-Hossain

**Abstract:**

This paper considers inference under progressive type II censoring with a compound Rayleigh failure time distribution. The maximum likelihood (ML), and Bayes methods are used for estimating the unknown parameters as well as some lifetime parameters, namely reliability and hazard functions. We obtained Bayes estimators using the conjugate priors for two shape and scale parameters. When the two parameters are unknown, the closed-form expressions of the Bayes estimators cannot be obtained. We use Lindley.s approximation to compute the Bayes estimates. Another Bayes estimator has been obtained based on continuous-discrete joint prior for the unknown parameters. An example with the real data is discussed to illustrate the proposed method. Finally, we made comparisons between these estimators and the maximum likelihood estimators using a Monte Carlo simulation study.

**Keywords:**
Monte Carlo Simulation,
maximum likelihood estimation,
Bayes estimation,
Progressive type II censoring,
compound Rayleigh failure time distribution,
Lindley's approximation method

##### 14 Maximum Likelihood Estimation of Burr Type V Distribution under Left Censored Samples

**Abstract:**

The paper deals with the maximum likelihood estimation of the parameters of the Burr type V distribution based on left censored samples. The maximum likelihood estimators (MLE) of the parameters have been derived and the Fisher information matrix for the parameters of the said distribution has been obtained explicitly. The confidence intervals for the parameters have also been discussed. A simulation study has been conducted to investigate the performance of the point and interval estimates.

**Keywords:**
Fisher information matrix,
confidence intervals,
Censoring

##### 13 On Bayesian Analysis of Failure Rate under Topp Leone Distribution using Complete and Censored Samples

**Abstract:**

The article is concerned with analysis of failure rate (shape parameter) under the Topp Leone distribution using a Bayesian framework. Different loss functions and a couple of noninformative priors have been assumed for posterior estimation. The posterior predictive distributions have also been derived. A simulation study has been carried to compare the performance of different estimators. A real life example has been used to illustrate the applicability of the results obtained. The findings of the study suggest that the precautionary loss function based on Jeffreys prior and singly type II censored samples can effectively be employed to obtain the Bayes estimate of the failure rate under Topp Leone distribution.

**Keywords:**
loss functions,
type II censoring,
posterior
distribution,
Bayes estimators

##### 12 Further Thoughtson a Sequential Life Testing Approach Using an Inverse Weibull Model

**Authors:**
D. I. De Souza,
G. P. Azevedo,
D. R. Fonseca

**Abstract:**

In this paper we will develop further the sequential life test approach presented in a previous article by [1] using an underlying two parameter Inverse Weibull sampling distribution. The location parameter or minimum life will be considered equal to zero. Once again we will provide rules for making one of the three possible decisions as each observation becomes available; that is: accept the null hypothesis H0; reject the null hypothesis H0; or obtain additional information by making another observation. The product being analyzed is a new electronic component. There is little information available about the possible values the parameters of the corresponding Inverse Weibull underlying sampling distribution could have.To estimate the shape and the scale parameters of the underlying Inverse Weibull model we will use a maximum likelihood approach for censored failure data. A new example will further develop the proposed sequential life testing approach.

**Keywords:**
Hypothesis testing,
Sequential Life Testing,
Maximum Likelihood Approach,
Inverse Weibull Model

##### 11 Additional Considerations on a Sequential Life Testing Approach using a Weibull Model

**Authors:**
D. I. De Souza,
D. R. Fonseca,
R. Rocha

**Abstract:**

**Keywords:**
Hypothesis testing,
Sequential Life Testing,
Underlying Weibull Model,
Maximum Likelihood Approach

##### 10 A New Brazilian Friction-Resistant Low Alloy High Strength Steel – A Life Testing Approach

**Authors:**
D. I. De Souza,
G. P. Azevedo,
R. Rocha

**Abstract:**

In this paper we will develop a sequential life test approach applied to a modified low alloy-high strength steel part used in highway overpasses in Brazil.We will consider two possible underlying sampling distributions: the Normal and theInverse Weibull models. The minimum life will be considered equal to zero. We will use the two underlying models to analyze a fatigue life test situation, comparing the results obtained from both.Since a major chemical component of this low alloy-high strength steel part has been changed, there is little information available about the possible values that the parameters of the corresponding Normal and Inverse Weibull underlying sampling distributions could have. To estimate the shape and the scale parameters of these two sampling models we will use a maximum likelihood approach for censored failure data. We will also develop a truncation mechanism for the Inverse Weibull and Normal models. We will provide rules to truncate a sequential life testing situation making one of the two possible decisions at the moment of truncation; that is, accept or reject the null hypothesis H0. An example will develop the proposed truncated sequential life testing approach for the Inverse Weibull and Normal models.

**Keywords:**
Sequential Life Testing,
Maximum Likelihood Approach,
normal and inverse Weibull models,
truncation mechanism

##### 9 Computational Aspects of Regression Analysis of Interval Data

**Authors:**
Michal Cerny

**Abstract:**

We consider linear regression models where both input data (the values of independent variables) and output data (the observations of the dependent variable) are interval-censored. We introduce a possibilistic generalization of the least squares estimator, so called OLS-set for the interval model. This set captures the impact of the loss of information on the OLS estimator caused by interval censoring and provides a tool for quantification of this effect. We study complexity-theoretic properties of the OLS-set. We also deal with restricted versions of the general interval linear regression model, in particular the crisp input – interval output model. We give an argument that natural descriptions of the OLS-set in the crisp input – interval output cannot be computed in polynomial time. Then we derive easily computable approximations for the OLS-set which can be used instead of the exact description. We illustrate the approach by an example.

**Keywords:**
Computational complexity,
Linear Regression,
interval-censored data

##### 8 Estimating Regression Parameters in Linear Regression Model with a Censored Response Variable

**Authors:**
Jesus Orbe,
Vicente Nunez-Anton

**Abstract:**

In this work we study the effect of several covariates X on a censored response variable T with unknown probability distribution. In this context, most of the studies in the literature can be located in two possible general classes of regression models: models that study the effect the covariates have on the hazard function; and models that study the effect the covariates have on the censored response variable. Proposals in this paper are in the second class of models and, more specifically, on least squares based model approach. Thus, using the bootstrap estimate of the bias, we try to improve the estimation of the regression parameters by reducing their bias, for small sample sizes. Simulation results presented in the paper show that, for reasonable sample sizes and censoring levels, the bias is always smaller for the new proposals.

**Keywords:**
Regression,
bias,
Censored response variable

##### 7 Duration Analysis of New Firms in the Banking Industry

**Authors:**
Jesus Orbe,
Vicente Nunez-Anton

**Abstract:**

This paper studies the duration or survival time of commercial banks active in the Moscovian three month Rouble deposits market, during the 1994-1997 period. The privatization process of the Russian commercial banking industry, after the 1988 banking reform, caused a massive entry of new banks followed by a period of high rates of exit. As a consequence, many firms went bankrupt without refunding their deposits. Therefore, both for the banks and for the banks- depositors, it is of interest to analyze which are the significant characteristics that motivate the exit or the closing of the bank. We propose a different methodology based on penalized weighted least squares which represents a very general, flexible and innovative approach for this type of analysis. The more relevant results are that smaller banks exit sooner, banks that enter the market in the last part of the study have shorter durations. As expected, the more experienced banks have a longer duration in the market. In addition, the mean survival time is lower for banks which offer extreme interest rates.

**Keywords:**
Banking,
Duration,
Kaplan-Meier,
censored

##### 6 A Renovated Cook's Distance Based On The Buckley-James Estimate In Censored Regression

**Authors:**
Nazrina Aziz,
Dong Q. Wang

**Abstract:**

There have been various methods created based on the regression ideas to resolve the problem of data set containing censored observations, i.e. the Buckley-James method, Miller-s method, Cox method, and Koul-Susarla-Van Ryzin estimators. Even though comparison studies show the Buckley-James method performs better than some other methods, it is still rarely used by researchers mainly because of the limited diagnostics analysis developed for the Buckley-James method thus far. Therefore, a diagnostic tool for the Buckley-James method is proposed in this paper. It is called the renovated Cook-s Distance, (RD* i ) and has been developed based on the Cook-s idea. The renovated Cook-s Distance (RD* i ) has advantages (depending on the analyst demand) over (i) the change in the fitted value for a single case, DFIT* i as it measures the influence of case i on all n fitted values Yˆ∗ (not just the fitted value for case i as DFIT* i) (ii) the change in the estimate of the coefficient when the ith case is deleted, DBETA* i since DBETA* i corresponds to the number of variables p so it is usually easier to look at a diagnostic measure such as RD* i since information from p variables can be considered simultaneously. Finally, an example using Stanford Heart Transplant data is provided to illustrate the proposed diagnostic tool.

**Keywords:**
censored data,
diagnostic analysis,
Buckley-James estimators,
censored regression,
product-limit estimator,
renovated Cook's Distance

##### 5 Discovery of Fuzzy Censored Production Rules from Large Set of Discovered Fuzzy if then Rules

**Authors:**
Tamanna Siddiqui,
M. Afshar Alam

**Abstract:**

**Keywords:**
Uncertainty quantification,
learning algorithm,
Fuzzy if then rules,
Fuzzy Censored Production Rules

##### 4 A Forward Automatic Censored Cell-Averaging Detector for Multiple Target Situations in Log-Normal Clutter

**Authors:**
Musa'ed N. Almarshad,
Saleh A. Alshebeili,
Mourad Barkat

**Abstract:**

**Keywords:**
probability of false alarm,
CFAR,
log-normal clutter,
Censoring,
Probabilityof detection,
Probability of falsecensoring

##### 3 Learning Classifier Systems Approach for Automated Discovery of Censored Production Rules

**Authors:**
Suraiya Jabin,
Kamal K. Bharadwaj

**Abstract:**

**Keywords:**
Data Mining,
Machine Learning,
Reinforcement Learning,
Censored Production Rule,
GeneticAlgorithm,
Learning Classifier System,
PittsburgApproach

##### 2 A Cumulative Learning Approach to Data Mining Employing Censored Production Rules (CPRs)

**Authors:**
Rekha Kandwal,
Kamal K.Bharadwaj

**Abstract:**

Knowledge is indispensable but voluminous knowledge becomes a bottleneck for efficient processing. A great challenge for data mining activity is the generation of large number of potential rules as a result of mining process. In fact sometimes result size is comparable to the original data. Traditional data mining pruning activities such as support do not sufficiently reduce the huge rule space. Moreover, many practical applications are characterized by continual change of data and knowledge, thereby making knowledge voluminous with each change. The most predominant representation of the discovered knowledge is the standard Production Rules (PRs) in the form If P Then D. Michalski & Winston proposed Censored Production Rules (CPRs), as an extension of production rules, that exhibit variable precision and supports an efficient mechanism for handling exceptions. A CPR is an augmented production rule of the form: If P Then D Unless C, where C (Censor) is an exception to the rule. Such rules are employed in situations in which the conditional statement 'If P Then D' holds frequently and the assertion C holds rarely. By using a rule of this type we are free to ignore the exception conditions, when the resources needed to establish its presence, are tight or there is simply no information available as to whether it holds or not. Thus the 'If P Then D' part of the CPR expresses important information while the Unless C part acts only as a switch changes the polarity of D to ~D. In this paper a scheme based on Dempster-Shafer Theory (DST) interpretation of a CPR is suggested for discovering CPRs from the discovered flat PRs. The discovery of CPRs from flat rules would result in considerable reduction of the already discovered rules. The proposed scheme incrementally incorporates new knowledge and also reduces the size of knowledge base considerably with each episode. Examples are given to demonstrate the behaviour of the proposed scheme. The suggested cumulative learning scheme would be useful in mining data streams.

**Keywords:**
Data Mining,
Machine Learning,
Censored production rules,
cumulative learning

##### 1 Evolutionary Approach for Automated Discovery of Censored Production Rules

**Authors:**
Kamal K. Bharadwaj,
Basheer M. Al-Maqaleh

**Abstract:**

**Keywords:**
Data Mining,
Evolutionary Algorithms,
machinelearning,
Censored Production Rule