Do cooperatives participation and technology adoption improve farmers’welfare in China?A joint analysis accounting for selection bias

This study examines the impact of farmers’cooperatives participation and technology adoption on their economic welfare in China.A double selectivity model(DSM)is applied to correct for sample selection bias stemming from both observed and unobserved factors,and a propensity score matching(PSM)method is applied to calculate the agricultural income difference with counter factual analysis using survey data from 396 farmers in 15 provinces in China.The findings indicate that farmers who join farmer cooperatives and adopt agricultural technology can increase agricultural income by 2.77 and 2.35%,respectively,compared with those non-participants and non-adopters.Interestingly,the effect on agricultural income is found to be more significant for the low-income farmers than the high-income ones,with income increasing 5.45 and 4.51%when participating in farmer cooperatives and adopting agricultural technology,respectively.Our findings highlight the positive role of farmer cooperatives and agricultural technology in promoting farmers’economic welfare.Based on the findings,government policy implications are also discussed.

Pregnancy is not a risk factor for gallstone disease: Results of a randomly selected population sample

AIM： To investigate the prevalence, risk factors, and selection of the study population for cholecystolithiasis in an urban population in Germany, in relation to our own findings and to the results in the international literature. METHODS： A total of 2 147 persons （1 111 females, age 42.8 ＋ 12.7 years; 1 036 males, age 42.3 ＋ 13.1 years） participating in an investigation on the prevalence of Echinococcus rnultilocularis were studied for risk factors and prevalence of gallbladder stone disease. Risk factors were assessed by means of a standardized interview and calculation of body mass index （BMI）. A diagnostic ultrasound examination of the gallbladder was performed. Data were analyzed by multiple logistic regression, using the SAS statistical software package. RESULTS： Gallbladder stones were detected in 171 study participants （8.0%, n = 2 147）. Risk factors for the development of gallbladder stone disease included age, sex, BMI, and positive family history. In a separate analysis of female study participants, pregnancy （yes/no） and number of pregnancies did not exert any influence. CONCLUSION： Findings of the present study confirm that age, female sex, BMI, and positive family history are risk factors for the development of gallbladder stone disease. Pregnancy and the number of pregnancies, however, could not be shown to be risk factors. There seem to be no differences in the respective prevalence for gallbladder stone disease in urban and rural populations.

Gastric cardia adenocarcinoma in Taiwan Residents men:Positive associations due to selection bias

The factors associated with an increase in gastric cardia adenocarcinoma are poorly understood.Environmental factors such as Helicobacter pylori(H.pylori) infection and diet have been hypothesized to play a role in the recently increased risk of this disease,but additional studies are needed.In conducting studies to establish the relationship between potential risk factors and gastric cardia adenocarcinoma,it is necessary to carefully consider the role of bias.In a recently published study,the reported associations between H.pylori as well as post-meal physical exertion and gastric cardia adenocarcinoma may have been greatly influenced by selection bias.

Comparing Methods of Applying the Propensity Score to Control Selection Bias in Studies of Prostate Cancer

To compare the performance of four common methods of applying propensity scores： covariate adjustment, stratification, matching, and inverse probability of treatment weighting, in addressing issues of selection bias. The linked Surveillance, Epidemiology, and End Results Medicare database was used in this study. We compared mortality of patients with localized prostate cancer, in two different scenarios. In Scenario 1, treatment effect on non-prostate cancer mortality were compared between patients with localized prostate cancer receiving active treatment （radical prostatectomy or radiation） and those only being observed. In Scenario 2, prostate cancer specific mortality was compared between localized prostate cancer patients with and without primary androgen deprivation therapy （ADT）. The known confounding factors of comorbidity （Scenario 1） or tumor grade （Scenario 2） were removed to evaluate the ability of each propensity score method to control for the selection bias caused by the presence of the factors. Matching yields slightly better control than the three other methods. None of the propensity score methods can eliminate bias caused by removing a known confounder.

The Importance of Selection Bias in Internet Surveys

Nowadays, internet-based surveys are increasingly used for data collection, because their usage is simple and cheap. Also they give fast access to a large group of respondents. There are many factors affecting internet surveys, such as measurement, survey design and sampling selection bias. The sampling has an important place in selection bias in internet survey. In terms of sample selection, the type of access to internet surveys has several limitations. There are internet surveys based on restricted access and on voluntary participation, and these are characterized by their implementation according to the type of survey. It can be used probability and non-probability sampling, both of which may lead to biased estimates. There are different ways to correct for selection biases;poststratification or weighting class adjustments, raking or rim weighting, generalized regression modeling and propensity score adjustments. This paper aims to describe methodological problems about selection bias issues and to give a review in internet surveys. Also the objective of this study is to show the effect of various correction techniques for reducing selection bias.

Research on Retrospective Studies of Real-World Study and Its Selection Bias

Objective To provide references for improving the authenticity and reliability of the retrospective study results,thus improving the quality of evidence in the real world and strengthening drug supervision and decision-making.Methods Literature review was used to study the data sources,the characteristics of retrospective research,the sources and the corrections of selective bias in the real world.Results and Conclusion The biases in retrospective study mainly come from admission rate bias,patient rate bias,survivors bias,health user bias and symptom bias.

Smallholder Adoption of Soil and Water Conservation Practices in Northern Ghana

Both governmental and non-governmental organizations are engaged in the promotion of soil and water conservation practices in Northern Ghana, but adoption is believed to be low. This study thus examines the determinants of conservation practices adoption by farming households in the area. Data for the study were collected from 445 households located in 15 communities in Northern Ghana. Univariate, bivariate and multivariate probit models were used to analyse the decision to adopt six conservation practices in the area. Results show that the major determinants of adoption are plot and cropping characteristics such as location; and socio-economic and institutional variables such as number of contacts with extension officers, membership in farmer association and distance to major market. A policy implication of the study is the strengthening of extension service in the area to significantly boost conservation adootion.

Security of biased BB84 quantum key distribution with finite resource

In the original BB84 quantum key distribution protocol, the states are prepared and measured randomly, which lose the unmatched detection results. To improve the sifting efficiency, biased bases selection BB84 protocol is proposed. Meanwhile, a practical quantum key distribution protocol can only transmit a finite number of signals, resulting in keys of finite length. The previous techniques for finite-key analysis focus mainly on the statistical fluctuations of the error rates and yields of the qubits. However, the prior choice probabilities of the two bases also have fluctuations by taking into account the finite-size effect. In this paper, we discuss the security of biased decoy state BB84 protocol with finite resources by considering all of the statistical fluctuations. The results can be directly used in the experimental realizations.

Enforcement actions and their effectiveness in securities regulation:Empirical evidence from management earnings forecasts

Due to resource constraints,securities regulators cannot find or punish all firms that have conducted irregular or even illegal activities(hereafter referred to as fraud).Those who study securities regulations can only find the instances of fraud that have been punished,not those that have not been punished,and it is these unknown cases that would make the best control sample for studies of enforcement action criteria.China's mandatory management earnings forecasts solve this sampling problem.In the A-share market,firms that have not forecasted as mandated are likely in a position to be punished by securities regulators or are attempting to escape punishment,and their identification allows researchers to build suitable study and control samples when examining securities regulations.Our results indicate that enforcement actions taken by securities regulators are selective.The probability that a firm will be punished for irregular management forecasting is significantly related to proxies for survival rates.Specifically,fraudulent firms with lower return on assets(ROAs) or higher cash flow risk are more likely to be punished.Further analysis shows that selective enforcement of regulations has had little positive effect on the quality of listed firms' management forecasts.

Assessing the Success of Masking in Acupuncture Trials:Further Insight

Editor： Hopton and MacPherson（1） are correct in noting that（1） attempts at masking are not always successful, hence（2） unsubstantiated claims of masking are not convincing, hence（3） guidance to cease assessing the success of masking should not be embraced. I take exception, however, to the authors calling this last point ＂controversial＂. I will concede that it is, in fact, controversial in the sense that tobacco was controversial at a time when certain medical groups still endorsed tobacco,