Genetic Family and Stock Type Influence Simulated Loblolly Pine Yields from Wet Sites

Planting adapted families or a bulked seedlot of bare-root and container-grown-seedlings of loblolly pine (Pinus taeda L) were contrasted as cost effective alternatives for regenerating Arkansas\u27 wet sites. Survival data from two wet sites were used to simulate 15 years of growth. Containerized seedlings provided 17% greater survival than bare-root seedlings, but yielded a lower present net worth than bare-root seedlings. Planting families adapted to excessive moisture provided 7% greater survival and yielded a greater present net worth than planting a bulked seedlot consisting of adapted and poorly adapted families

Estimating excess hazard ratios and net survival when covariate data are missing: strategies for multiple imputation.

BACKGROUND: Net survival is the survival probability we would observe if the disease under study were the only cause of death. When estimated from routinely collected population-based cancer registry data, this indicator is a key metric for cancer control. Unfortunately, such data typically contain a non-negligible proportion of missing values on important prognostic factors (eg, tumor stage). METHODS: We carried out an empirical study to compare the performance of complete records analysis and several multiple imputation strategies when net survival is estimated via a flexible parametric proportional hazards model that includes stage, a partially observed categorical covariate. Starting from fully observed cancer registry data, we induced missingness on stage under three scenarios. For each of these scenarios, we simulated 100 incomplete datasets and evaluated the performance of the different strategies. RESULTS: Ordinal logistic models are not suitable for the imputation of tumor stage. Complete records analysis may lead to grossly misleading estimates of net survival, even when the missing data mechanism is conditionally independent of survival time given the covariates and the bias on the excess hazard ratios estimates is negligible. CONCLUSIONS: As key covariates are unlikely missing completely at random, studies estimating net survival should not use complete records. When the missingness can be inferred from available data, appropriate multiple imputation should be performed. In the context of flexible parametric proportional hazards models with a partially observed stage covariate, a multinomial logistic imputation model for stage should be used and should include the Nelson-Aalen cumulative hazard estimate and the event indicator

Circular 116

Free-range reindeer in western Alaska are managed for both velvet antler and meat production. Optimal management should maximize the income generated from both meat and antler production while managing the herd at levels below the carrying capacity of the range. Meat production precludes future antler production from harvested animals, therefore harvest decisions should reflect antler and body growth rates, current antler and meat prices, natural survival rates, and population demographics. We present a user-friendly computer model to generate estimates of net income under different harvest levels and market conditions. Input variables include sex- and agespecific survival rates, harvest levels, castration rates, antler weights, body weights, and recapture rates, as well as reproductive rates, fixed and variable costs, antler price, and meat price. Mark—Recapture analysis was used to estimate survival rates. The model was calibrated using reindeer herd records from 1984-1997. Output includes changes in herd size and composition over a thirty-year period, meat production, antler production, female: male ratio, and predicted net income. The model illustrates the sensitivity of herd size to female adult survival rates

Net Neutrality: Fight for the Survival of the Free Internet

The Internet is often thought of as a tool that allows for the free flow of information. Today, as a vessel of free speech, the Internet threatens to become a vestige of its original self. Increasingly, Internet Service Providers (ISPs) claim the power to regulate content and arbitrarily increase the price for customers to access certain information and have the ability to make customers financially support content that they disagree with. In these ways, ISPs have gained increased control over the flow of Internet information, while the citizen of cyberspace has increasingly lost his freedom to control his choices online. This poses an even more important problem for American democracy, which demands educated citizens, who are threatened by censorship. Only a libertarian approach to this problem, which sustains the original ideals of the Internet as a tool of unfiltered communication, will continue freedom of information. The best implementations of the libertarian approach are net neutrality laws, which ensure that all users are treated equally. This paper argues to support both the need for net neutrality laws to protect against economically driven encroachment upon the freedom of the Internet and the importance of libertarian ideas to the maintenance and strengthening of democracy

The impact of life tables adjusted for smoking on the socio-economic difference in net survival for laryngeal and lung cancer.

BACKGROUND: Net survival is a key measure in cancer control, but estimates for cancers that are strongly associated with smoking may be biased. General population life tables represent background mortality in net survival, but may not adequately reflect the higher mortality experienced by smokers. METHODS: Life tables adjusted for smoking were developed, and their impact on net survival and inequalities in net survival for laryngeal and lung cancers was examined. RESULTS: The 5-year net survival estimated with smoking-adjusted life tables was consistently higher than the survival estimated with unadjusted life tables: 7% higher for laryngeal cancer and 1.5% higher for lung cancer. The impact of using smoking-adjusted life tables was more pronounced in affluent patients; the deprivation gap in 5-year net survival for laryngeal cancer widened by 3%, from 11% to 14%. CONCLUSIONS: Using smoking-adjusted life tables to estimate net survival has only a small impact on the deprivation gap in survival, even when inequalities are substantial. Adjusting for the higher, smoking-related background mortality did increase the estimates of net survival for all deprivation groups, and may be more important when measuring the public health impact of differences or changes in survival, such as avoidable deaths or crude probabilities of death

Estimation of net survival for cancer patients: Relative survival setting more robust to some assumption violations than cause-specific setting, a sensitivity analysis on empirical data.

Net survival is the survival that would be observed if the only possible underlying cause of death was the disease under study. It can be estimated with either cause-specific or relative survival data settings, if the informative censoring is properly considered. However, net survival estimators are prone to specific biases related to the data setting itself. We examined which data setting was the most robust against violation of key assumptions (erroneous cause of death and inappropriate life tables). We identified 4285 women in the Geneva Cancer Registry, diagnosed with breast, colorectal, lung cancer and melanoma between 1981 and 1991 and estimated net survival up to 20 years using cause-specific and relative survival settings. We used weights to tackle informative censoring in both settings and performed sensitivity analyses to evaluate the impact of misclassification of cause of death in the cause-specific setting or of using inappropriate life tables on net survival estimates in the relative survival setting. For all the four cancers, net survival was highest when using the cause-specific setting and the absolute difference between the two estimators increased with time since diagnosis. The sensitivity analysis showed that (i) the use of different life tables did not compromise net survival estimation in the relative survival setting, whereas (ii) a small level of misclassification for the cause of death led to a large change in the net survival estimate in the cause-specific setting. The relative survival setting was more robust to the above assumptions violations and is therefore recommended for estimation of net survival

Cause-specific or relative survival setting to estimate population-based net survival from cancer? An empirical evaluation using women diagnosed with breast cancer in Geneva between 1981 and 1991 and followed for 20 years after diagnosis.

BACKGROUND: Both cause-specific and relative survival settings can be used to estimate net survival, the survival that would be observed if the only possible underlying cause of death was the disease under study. Both resulting net survival estimators are biased by informative censoring and prone to biases related to the data settings within which each is derived. We took into account informative censoring to derive theoretically unbiased estimators and examine which of the two data settings was the most robust against incorrect assumptions in the data. PATIENTS AND METHODS: We identified 2489 women in the Geneva Cancer Registry, diagnosed with breast cancer between 1981 and 1991, and estimated net survival up to 20-years using both cause-specific and relative survival settings, by tackling the informative censoring with weights. To understand the possible origins of differences between the survival estimates, we performed sensitivity analyses within each setting. We evaluated the impact of misclassification of cause of death and of using inappropriate life tables on survival estimates. RESULTS: Net survival was highest using the cause-specific setting, by 1% at one year and by up to around 11% twenty years after diagnosis. Differences between both sets of net survival estimates were eliminated after recoding between 15% and 20% of the non-specific deaths as breast cancer deaths. By contrast, a dramatic increase in the general population mortality rates was needed to see the survival estimates based on relative survival setting become closer to those derived from cause-specific setting. CONCLUSION: Net survival estimates derived using the cause-specific setting are very sensitive to misclassification of cause of death. Net survival estimates derived using the relative-survival setting were robust to large changes in expected mortality. The relative survival setting is recommended for estimation of long-term net survival among patients with breast cancer

Reflex impairment as a measure of vitality and survival potential of Atlantic cod (Gadus morhua)

A ssur ing the v itality and survival potential of live-caught Atlantic cod (Gadus morhua) is important for improving the sorting of fish before net penning operations designed to hold fish for growth and later market. When Atlantic cod are captured by Danish seine, the most commonly used fishing gear for live-caught fish, they undergo stressors such as forced swimming, net abrasion, and air exposure. Laboratory experiments (at an air temperature of 9°C and water temperature of 8°C) were conducted with the aim of constructing a RAMP (reflex action mortality predictor) curve for prediction of vitality and survival potential in Atlantic cod captured in Danish seines, by varying the levels of these stressors. Atlantic cod exposed to increased duration in air (5–20 min) showed increased reflex impairment and mortality, with 75% mortality at 10 minutes of air exposure. Forced swimming in combination with net abrasion and air exposure did not increase reflex impairment or mortality above that associated with air exposure alone. The Atlantic cod RAMP curves indicated that fish with reflex impairment less than 50% would not show mortality and would likely recover from capture stress

Why Do Cooperatives Fail? Big versus Small in Ghanaian Cocoa Producers’ Societies, 1930-36

Using a complete panel of Ghanaian cocoa producers’ societies in the 1930s, we investigate whether group interaction problems threatened i) capital accumulation, ii) cocoa sales and iii) cooperative survival as membership size increased. We find evidence of group interaction problems. The net effect, however, is positive indicating gains from economies of scale as cooperatives expanded their membership.cooperatives, firm survival, collective action problems, Ghana

Why do cooperatives fail? Big versus small in Ghanaian Cocoa Producers' Societies, 1930-36

Using a complete panel of Ghanaian cocoa producers’ societies in the 1930s, we investigate whether group interaction problems threatened i) capital accumulation, ii) cocoa sales and iii) cooperative survival as membership size increased. We find evidence of group interaction problems. The net effect, however, is positive indicating gains from economies of scale as cooperatives expanded their membership.cooperatives, firm survival, collective action problems, Ghana