Estimation and identification issues in the promotion time cure model when the same covariates influence long‐ and short‐term survival

The promotion time cure model is a survival model acknowledging that an unidentified proportion of subjects will never experience the event of interest whatever the duration of the follow‐up. We focus our interest on the challenges raised by the strong posterior correlation between some of the regression parameters when the same covariates influence long‐ and short‐term survival. Then, the regression parameters of shared covariates are strongly correlated with, in addition, identification issues when the maximum follow‐up duration is insufficiently long to identify the cured fraction. We investigate how, despite this, plausible values for these parameters can be obtained in a computationally efficient way. The theoretical properties of our strategy will be investigated by simulation and illustrated on clinical data. Practical recommendations will also be made for the analysis of survival data known to include an unidentified cured fraction.     

Impact of two follow-up schemes on morbidity management and disability prevention (MMDP) programme for filarial lymphedema in Matara,Sri Lanka

Alleviating morbidity due to lymphatic filariasis (LF)—especially in elderly patients who are rather ignorant—is presently the biggest challenge for the national filariasis campaign. We introduced two follow-up schemes and compared each other to address three key programmatic issues (1) locating patients, (2) educating patients, family members on practice of lymphoedema self-care (3) well sustained daily self-care. Hundred and seven lymphoedema patients were introduced to the new Community Home Based Care (CHBC) programme as a part of MMDP programme at their homes. Twenty seven of 107 patients were selected by purposive sampling and followed-up under two schemes, 14 in Daily follow-up (DFU) scheme and 13 in Monthly follow-up (MFU) scheme. Impact was assessed using a KAP score, number of entry lesions (EL) and number of ADL episodes, limb volume, its appearance, changes in the quality of life and gained benefits. Visiting patients in their homes to introduce lymphoedema care programme was a success. KAP scores of the more important activities on lymphoedema care were significantly higher in DFU scheme. Number of patients (51.9%; 14/27) who had EL/s at baseline reduced significantly to 18.5% (5/27) at one year follow-up. The mean numbers of ADL episodes/year reduced significantly in both schemes. Six photographs of 27 showed obvious improvement in lymphoedema and its grade. Mean volume of lymphoedema reduced significantly in both schemes at one year no significant difference between schemes. Benefit score at one year revealed that the patients in DFU scheme received significantly higher amount of benefits compared to MFU scheme. In conclusion daily instruction has significantly motivated the patient and his/her family bringing a new hope.     

Estimating emission coefficients and mass balances using economic data: A stochastic frontier approach

In this article, we propose a stochastic formulation of mass balances that impose physical constraints on production technologies. The estimation of the model involves a composed error term structure that is commonly applied in the literature on stochastic frontier analysis of productive efficiency. Moreover, we discuss how ordinary least squares and maximum likelihood methods can be used to estimate emission coefficients based on the proposed model and compare the results to estimates based on linear programming techniques from input–output analysis. In contrast to previous approaches, our model allows one to estimate the physical limitations to production possibilities in the presence of statistical noise and depends on substantially weaker data requirements. We apply our approach to estimate emission coefficients for sulfur dioxide and carbon dioxide using a sample of fossil‐fueled power plants in the United States.     

Economic transformation and biological welfare in colonial Burma: Regional differentiation in the evolution of average height

Did economic development result in an improvement in biological welfare in the tropics before the diffusion of modern public health techniques in the 1950s and 1960s? Between the mid-19th and early 20th century, Lower Burma experienced a rapid rise in population and became increasingly commercialized as a major rice exporter. Land reclamation on a massive scale in the Irrawaddy delta required an arduous process of jungle clearance, land drainage and preparation, and canal and bund construction, mostly in malarial swamps. Once paddy lands were created, rice was grown with rudimentary tools in malarial zones. By contrast, in most parts of Upper Burma the economy remained more subsistence-oriented, and less commercialized. In this paper, we investigate changes in physical stature by processing and analyzing data reported in two anthropometric surveys conducted in various regions of Upper and Lower Burma in 1904 and in 1938-1941. An inverted U curve is observed in the evolution of average height in Lower Burma, while stature remained fairly stable in Upper Burma until the 1930s.