Determinants of herbicide use in rice production in the Philippines

This study identifies farm‐specific and market factors affecting the adoption of herbicides and the level of herbicide use by rice farmers in the Philippines. This requires the application of a modified version of Heckman's two‐step method to estimate a random‐effects double‐hurdle model for unbalanced panel data. The age of the farmer, household size, and irrigation use are significant determinants of the decision of farmers to adopt herbicides as an alternative to manual weeding, while economic variables such as the price of herbicides, total income, and access to credit determine the level of herbicide use. Determinants of both adoption and level are land ownership, farm area, and the method of crop establishment. These results are potentially relevant when designing policies to reduce excessive herbicide use or to encourage the adoption of alternative weed control methods such as integrated weed management.     

Sentences Recognition Memory and Extraversion-Introversion Levels: A Statistical Modelling Approach

This research aimed to analyse individual differences in recognition of semantic memory by means of a statistical modelling approach, because some difficulties arise when traditional experimental designs and statistical hypotheses tests are used. In this field, statistical modelling provides the possibility of obtaining a data-fitted model for each experimental condition. One hundred and thirty five adult students, both males and females, agreed to participate in our study and were classified as high, middle and low extraverts. Sentences with a high semantic organisation were used as material to be recognised. A statistical modelling process was then applied using the lEM program. Differences in recognition memory for hits were found between middle and low extraversion levels, as revealed by the different data-fitted models.