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In regression modeling, we often encounter data with different ranges. Such data usually have outliers. If an outlier has a value far from the mean, it can cause an error in modeling. For example, data has a quadratic pattern, but because there are outliers, it can be indicated that the data is linear. This research will prove which non-linearity test is more robust if outlier data is shown. To prove this, data is generated, and outliers are found in the variable response of the nonlinear model. Using the RESET, the Terasvirta and White tests will prove to be more robust. The results show that the Terasvirta test is more robust than the RESET and White tests. This statement applies to models that are non-linear in parameters and variables. Therefore, if we want to test the goodness of a non-linear model and outliers are detected from our research, we recommend using the Terasvirta test. We prove that 53.42% of Terasvirta performs better than the RESET and White tests. Because the Terasvirta test is proven to be more robust if outliers are found in the non-linear model, this is very important to increase knowledge in education, especially in computing statistics. [ABSTRACT FROM AUTHOR]

Deploying data centers in the waters near coastal cities can greatly reduce the distance between data and users, not only eliminating the need to occupy land resources, but also saving energy consumption, which is a completely green and sustainable data center solution. Under the background of resource conservation and green development, this paper puts forward the project of undersea data center heat dissipation. Through the establishment of multiple linear regression model, the influence of tidal and seasonal changes on the heat dissipation of undersea data center is analyzed. Finally, it is concluded that the seasonal changes have the greatest impact on the heat dissipation of the undersea data center container. In the future, the placement strategy of data center and the methods to improve the heat dissipation efficiency will be further discussed. [ABSTRACT FROM AUTHOR]

Abstract Background Acute pancreatitis after liver resection is a rare but serious complication, and few cases have been described in the literature. Extended lymphadenectomy, and long ischemia due to the Pringle maneuver could be responsible of post-liver resection acute pancreatitis, but the exact causes of AP after hepatectomy remain unclear. Cases presentation We report here three cases of AP after hepatectomy and we strongly hypothesize that this is due to the bile leakage white test. 502 hepatectomy were performed at our center and 3 patients (0.6%) experienced acute pancreatitis after LR and all of these three patients underwent the white test at the end of the liver resection. None underwent additionally lymphadenectomy to the liver resection. All patient had a white-test during the liver surgery. We identified distal implantation of the cystic duct in these three patients as a potential cause for acute pancreatitis. Conclusion The white test is useful for detection of bile leakage after liver resection, but we do not recommend a systematic use after LR, because severe acute pancreatitis can be lethal for the patient, especially in case of distal cystic implantation which may facilitate reflux in the main pancreatic duct.

Background: Acute pancreatitis after liver resection is a rare but serious complication, and few cases have been described in the literature. Extended lymphadenectomy, and long ischemia due to the Pringle maneuver could be responsible of post-liver resection acute pancreatitis, but the exact causes of AP after hepatectomy remain unclear.Cases Presentation: We report here three cases of AP after hepatectomy and we strongly hypothesize that this is due to the bile leakage white test. 502 hepatectomy were performed at our center and 3 patients (0.6%) experienced acute pancreatitis after LR and all of these three patients underwent the white test at the end of the liver resection. None underwent additionally lymphadenectomy to the liver resection. All patient had a white-test during the liver surgery. We identified distal implantation of the cystic duct in these three patients as a potential cause for acute pancreatitis.Conclusion: The white test is useful for detection of bile leakage after liver resection, but we do not recommend a systematic use after LR, because severe acute pancreatitis can be lethal for the patient, especially in case of distal cystic implantation which may facilitate reflux in the main pancreatic duct. [ABSTRACT FROM AUTHOR]

Background Bile leakage is a common and serious complication after hepatic resection. It is important to prevent it by early detection and repair of leaking points intraoperatively and hence minimizing postoperative leaks. In this study, the authors prospectively compared the effect of transcystic intralipid injection versus saline test and then cholangiography on biliary complications in different cases of liver resection. Patients and methods This is a prospective randomized clinical trial in which we compared between the use of the White test and the use of saline test followed by cholangiography for the intraoperative detection of bile leakage in patients who underwent liver resection with cholecystectomy. The 52 cases were carried out in the National Liver Institute from May 2019 till March 2021. Results The incidence of postoperative bile leakage in both groups was compared. Bile leakage occurred in nine (34.6%) patients in the conventional saline and then cholangiography and in three (11.5%) patients in the White test group; this was statistically significant (P=0.048). In addition, the White test detected intraoperatively a significantly larger number of bile leakage sites (seven cases) compared with the saline and then cholangiography group (two cases). Conclusion Based on the results of this study, the authors strongly recommend using the white test to saline test and then cholangiography as the bile leak test of choice in minimizing posthepatectomy bile leak. [ABSTRACT FROM AUTHOR]

Given the effect that outliers can have on regression and specification testing, a vastly used robustification strategy by practitioners consists in: (i) starting the empirical analysis with an outlier detection procedure to deselect atypical data values; then (ii) continuing the analysis with the selected non-outlying observations. The repercussions of such robustifying procedure on the asymptotic properties of subsequent inferential procedures are, however, underexplored. We study the effects of such a strategy on testing for heteroscedasticity. Specifically, using weighted and marked empirical processes of residuals theory, we show that the White test implemented after the outlier detection and removal is asymptotically chi-square if the underlying errors are symmetric. In a simulation study, we show that—depending on the type of outliers—the standard White test can be either severely undersized or oversized, as well as have trivial power. The statistic applied after deselecting outliers has good finite sample properties under symmetry but can suffer from size distortions under asymmetric errors. Given these results, we devise an empirical modeling strategy to guide practitioners whose preferred approach is to remove outliers from the sample. [ABSTRACT FROM AUTHOR]

Heteroscedasticity occurs mostly because of beneath mistakes in variable, incorrect data transformation, incorrect functional form, omission of important variables, non-detailed model, outliers and skewness in the distribution of one or more independent variables in the model. All analysis were carried out in R statistical package using Imtest, zoo and package.base. Five heteroscedasticity tests were selected, which are Park test, Glejser test, Breusch-Pagan test, White test and Goldfeld test, and used on simulated datasets ranging from 20,30,40,50,60,70,80,90 and 100 sample sizes respectively at different level of heteroscedasticity (that is at low level when sigma = 0.5, mild level when sigma = 1.0 and high level when sigma = 2.0). Also, the significance criterion alpha = 0.05. However, each test was repeated 1000 times and the percentage of rejection was computed over 1000 trials. For Glejser test, the average empirical type I error rate for the test reject more than expected while Goldfeld has the least power value. Therefore, Glejser test has the highest capacity to detect heteroscedasticity in most especially on simulated datasets. [ABSTRACT FROM AUTHOR]

In this paper we provide considerable Monte Carlo evidence on the finite sample performance of several alternative forms of White's [1982] IM test. Using linear regression and probit models, we extend the range of previous analysis in a manner that reveals new patterns in the behavior of the asymptotic version of the IM test - particularly with respect to curse of dimensionality effects. We also explore the potential of parametric and nonparametric bootstrap methods for reducing the size bias that characterizes the asymptotic IM test. The nonparametric bootstrap is of particular interest because of the weak conditions it imposes, but the results of our Monte Carlo experiments suggest that this technique is not without limitations. The parametric bootstrap demonstrates good size and power in reasonably small samples, but requires assumptions that may be auxiliary from the standpoint of a QMLE. We observe that the effects of violating one of these auxiliary assumptions has a non-trivial impact on the size of IM tests that employ this technique.

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Background Intraoperative bile leakage testing is an important procedure in liver resection as it helps in detection of bile leaking points on the cut surface, thereby decreases postoperative bile leakage, which is one of the most dreadful complications following liver surgery. In this study, we tried to assess the efficacy of using White test in comparison with conventional saline test in detecting intraoperative bile leakage. Patients and methods In this study, we assessed whether the White test is better than the conventional saline test for the intraoperative detection of bile leakage in patients undergoing liver resection. This study included 100 patients who underwent elective liver resection. The conventional saline test (injecting an isotonic sodium chloride solution through the cystic duct) was carried out in 50 patients and the White test (injecting a fat emulsion solution through the cystic duct) was carried out in 50 patients. Results Incidence of postoperative bile leakage was compared between the conventional method and the White test. Bile leakage occurred in 22 (44%) patients in the conventional method group and in four (8%) patients in the White test group. In addition, the White test detected intraoperatively a significantly higher number of bile leakage sites compared with the conventional method. Therefore, the White test seems to be better than the conventional test for the intraoperative detection of bile leakage. Conclusion Based on our study, we recommend that surgeons investigating bile leakage sites during liver resections should use the White test instead of the conventional saline test. [ABSTRACT FROM AUTHOR]

The present study investigated the factors affecting off-farm employment of small farmers in Peshawar Valley. A sample of 201 small farmers were selected using random sampling technique and data were collected through a pre-tested interview schedule. This study focuses on two selected districts i.e. Peshawar, and Charsadda. Four villages were selected two each from the sampled districts. Analysis showed that the coefficients of household size, educational level of the sampled respondent, age of the sample small farmer, were positively related to the off-farm employment. While farm area operated was negatively but significantly related to off-farm employment. Similarly the small farm households of developed villages perform more off-farm employment than the small farm households of underdeveloped villages. This could be associated to the developed means of transport and communications, better education facilities, market facilities as well as availability of off-farm jobs locally. In developed villages of two districts, average per month income of sample small farmers from farm output was higher than the undeveloped villages of these districts due to the high sale price of vegetables grown on large area and more milk production. Similarly, in developed villages income from off-farm employment was more than undeveloped villages. Because large number of family labors of sample respondents were working on high paid jobs or employed else or self-employed and thus contributed a good amount to their family's income. The study recommends that unemployment in the agriculture sector is likely to increase with the decrease in the size of holdings. To generate off-farm employment opportunities agro based industries seems to potential area. Simultaneously there is need for initiating skill development programs. [ABSTRACT FROM AUTHOR]

This paper shows that a test for heteroskedasticity within the context of classical linear regression can be based on the difference between Wald statistics in heteroskedasticity-robust and nonrobust forms. The test is asymptotically distributed under the null hypothesis of homoskedasticity as chi-squared with one degree of freedom. The power of the test is sensitive to the choice of parametric restriction used by the Wald statistics, so the supremum of a range of individual test statistics is proposed. Two versions of a supremum-based test are considered: the first version does not have a known asymptotic null distribution, so the bootstrap is employed to approximate its empirical distribution. The second version has a known asymptotic distribution and, in some cases, is asymptotically pivotal under the null. A simulation study illustrates the use and finite-sample performance of both versions of the test. In this study, the bootstrap is found to provide better size control than asymptotic critical values, namely with heavy-tailed, asymmetric distributions of the covariates. In addition, the use of well-known modifications of the heteroskedasticity consistent covariance matrix estimator of OLS coefficients is also found to benefit the tests' overall behaviour. [ABSTRACT FROM AUTHOR]

We present a new stopping criterion for the matching pursuit (MP) algorithm, based on evaluating stationarity of the residua of the consecutive MP iterations. The new stopping criterion is based on a model of a nonstationary signal, which assumes that the part of the signal that is of interest is nonstationary and contaminated by a weakly stationary noise. Mean- and variance-stationarity of the residua obtained from each step of MP is evaluated by means of dedicated statistical tests-the Kwiatkowski-Phillips-Schmidt-Shin (KPSS) test and the White test, respectively. We illustrate the proposed concept by an example in which we analyse magnetoencephalographic (MEG) data. [ABSTRACT FROM AUTHOR]

Stationarity is a crucial yet rarely questioned assumption in the analysis of time series of magneto- (MEG) or electroencephalography (EEG). One key drawback of the commonly used tests for stationarity of encephalographic time series is the fact that conclusions on stationarity are only indirectly inferred either from the Gaussianity (e.g. the Shapiro-Wilk test or Kolmogorov-Smirnov test) or the randomness of the time series and the absence of trend using very simple time-series models (e.g. the sign and trend tests by Bendat and Piersol). We present a novel approach to the analysis of the stationarity of MEG and EEG time series by applying modern statistical methods which were specifically developed in econometrics to verify the hypothesis that a time series is stationary. We report our findings of the application of three different tests of stationarity-the Kwiatkowski-Phillips-Schmidt-Schin (KPSS) test for trend or mean stationarity, the Phillips-Perron (PP) test for the presence of a unit root and the White test for homoscedasticity-on an illustrative set of MEG data. For five stimulation sessions, we found already for short epochs of duration of 250 and 500 ms that, although the majority of the studied epochs of single MEG trials were usually mean-stationary (KPSS test and PP test), they were classified as nonstationary due to their heteroscedasticity (White test). We also observed that the presence of external auditory stimulation did not significantly affect the findings regarding the stationarity of the data. We conclude that the combination of these tests allows a refined analysis of the stationarity of MEG and EEG time series. [ABSTRACT FROM AUTHOR]

In practice it is very difficult to distinguish between stochastic and chaotic nonlinearity. It is also difficult to identify nonlinear structures in time series when the hidden dynamics are complex. In this paper, we provide evidence that in the presence of specific high-dimensional underlying structures, White [1989] and Theiler et al. [1992] tests fail to detect nonlinearity. [ABSTRACT FROM AUTHOR]

Background: Intra-operative bile leakage testing is very important in partial liver resection in living donor liver transplant as it allows detection of bile leaking points on the cut surface and decreases postoperative bile leak which is one of the most dreadful complication following liver transplant surgery. In this study we tried to assess the Effectiveness of White test versus conventional saline test in minimizing biliary leak in partial liver resection in living donor liver transplant. Objective: In this study, we assess whether the White test is better than the conventional saline test for the intraoperative detection of biliary leakage in patients who will undergo partial liver resection as living donor liver transplant. Methodology: In this study, we assess whether the White test is better than the conventional saline test for the intraoperative detection of bile leakage in patients who underwent partial liver resection as a living donor liver transplant. This study included 60 patients who received partial liver resection as a living donor liver transplant. The conventional saline test (injecting an isotonic sodium chloride solution through the cystic duct) was carried out in 30 patients and the White test (injecting a fat emulsion solution through the cystic duct) was carried out in 30 patients Results: Incidence of postoperative bile leakage was compared between the conventional method and the White test. Bile leakage occurred in 8 patients (26.7%) in the conventional method group and in 2 patients (6.7%) in the White test group. In addition, the White test detected intraoperative a significantly higher number of bile leakage sites compared with the conventional method. The White test is better than the conventional test for the intraoperative detection of bile leakage. Conclusion: Based on our study, we recommend that surgeons investigating bile leakage sites during liver resections should use the White test instead of the conventional saline test. [ABSTRACT FROM AUTHOR]

Background: Hepatic surgery will be always one of the most challenging surgical procedures due to its anatomical and pathophysiologic varieties. Various problems may complicate the post-operative course. Bile leak remains a serious complication after hepatectomy. Bile leaks can significantly impact morbidity, mortality, and cost of treatment. Bile leak increases risk of sepsis, need for further intervention, either radiological or return to theatre, prolongs duration of intensive care unit and hospital stay, and can precipitate liver failure and death. Objective: To assess the post-operative bile leak complication after using white test versus conventional saline test Patients and Methods: A prospective study on 50 Hepatectomy cases divided into two groups, the first group consist of 25 cases using white test and the second group consist of 25 cases using conventional saline test from January 2019 to January 2020, at Hepatobiliary unit of the general surgery department of Ain Shams university hospitals. Results: The White test has clear advantages in comparison with other bile leakage tests: it precisely detects bile leakages, regardless of size; it does not stain the resection surface, allowing it to be washed off and repeated ad infinitum; and it is safe, quick, and inexpensive. The white test is a feasible and sensitive bile leakage test with no obvious disadvantages. It could be a possible standardized method to prevent bile leakage in major liver resection. Conclusion: Now after we discussed our study and reviewed other opinions discussing the optimal methods for intraoperative bile leakage testing, we have now settled on White test using fat emulsion solution to be best of all tests. [ABSTRACT FROM AUTHOR]

In this article, we investigate individual consumption data of natural gas and electricity using modified multiple regression techniques. Because a subset of households have zero gas consumption, the purpose of the study is to ask two empirical questions: 1. How can we quantify potential energy conservation from increasing gas availability? 2. Is it appropriate to estimate and compare electricity demands of gas users and nonusers by the same regression function? We began our investigation based on the methodology of generalized tobit models. Our empirical results indicate that the probit equation for gas connection is exogenous to the amount of potential energy consumption. To answer question 2, we obtain heteroscedasticity-efficient estimates of the electricity-demand equations by a nearest-neighbor estimator to deal with heteroscedasticity of unknown form. The prediction of energy conservation is that electricity demand could be reduced by 2,473.57 kilowatt-hours a year per household if a gas connection is available to nonusers. To reduce electricity demand by this amount, the utility company would need to supply 611.09 Therms of natural gas. [ABSTRACT FROM AUTHOR]