THE VALIDITY OF THE INDEPENDENT INCREMENTS ASSUMPTION FOR PRODUCTION: AN EMPIRICAL STUDY OF AN AUTOMOTIVE ASSEMBLY PLANT

In assembly plants, random line stoppages cause production variability. For analytic tractability and data availability, researchers commonly assume that the production process possesses the independent increments property (necessary for a process to be Poisson). If the production process has independent increments, then the production in any interval is independent of the production in any other nonoverlapping interval. This property means, for one thing, that the current period's production is never influenced by previous production periods. Intuition, however, suggests that current production could be correlated to past production-violating this assumption of independence. If production problems persist from one period to the next, then one would expect the production in adjacent time periods to be correlated. Although the independent increments property is oflen assumed, its validity has not been demonstrated in practice. We analyze data from an automotive assembly plant to assess the validity of the independent increments assumption for its production.     

Export Agriculture and Development Path: Independent Farming in Comparative Perspective

Abstract This paper compares 'regions of "recent settlement' (Australia, Canada, the United States, and New Zealand) and Argentina to help assess the conditions under which export oriented agrarian regions and societies adopt a development path oriented to industrialization, focusing on the 1860s through the 1930s. The paper surveys the available literature to trace how agricultural export sector expansion shaped land tenure, class formation, and agrarian political participation in these societies. It sketches the class alliances and related structural conditions shaping the development path adopted. The regions of recent settlement tended to share a pattern of agrarian social structure and mobilization characterized by a high incidence of family operated farms, relatively little landlord predominance, strong farmer mobilization, and a class alliance and polity adhering to a consensus on industrialization and basic policies. Argentina represents a contrasting case in which landlords prevailed. The paper contributes to broader theoretical debate by relating the impact of export agriculture to the internal organization of the export sector.     

General mixed‐data model: Extension of general location and grouped continuous models

The authors propose a general model for the joint distribution of nominal, ordinal and continuous variables. Their work is motivated by the treatment of various types of data. They show how to construct parameter estimates for their model, based on the maximization of the full likelihood. They provide algorithms to implement it, and present an alternative estimation method based on the pairwise likelihood approach. They also touch upon the issue of statistical inference. They illustrate their methodology using data from a foreign language achievement study.     

Dynamic Analysis of Recurrent Event Data with Missing Observations, with Application to Infant Diarrhoea in Brazil

Abstract.  This paper examines and applies methods for modelling longitudinal binary data subject to both intermittent missingness and dropout. The paper is based around the analysis of data from a study into the health impact of a sanitation programme carried out in Salvador, Brazil. Our objective was to investigate risk factors associated with incidence and prevalence of diarrhoea in children aged up to 3 years old. In total, 926 children were followed up at home twice a week from October 2000 to January 2002 and for each child daily occurrence of diarrhoea was recorded. A challenging factor in analysing these data is the presence of between-subject heterogeneity not explained by known risk factors, combined with significant loss of observed data through either intermittent missingness (average of 78 days per child) or dropout (21% of children). We discuss modelling strategies and show the advantages of taking an event history approach with an additive discrete time regression model.     

Evaluation of an easy to read parent-held information and record booklet of child health

SUMMARY. An evaluation of the Nottingham parent-held record and information booklet is presented. The book was well used by the majority of parents with 80 per cent of the parents having read all the booklet by the time their babies were three months old. 70 per cent of the parents had retained the booklet when their children had reached the age of one year