The classification of a Sesbania sesban (sssesban) collection. II. Agronomic attributes and their relation to biomass estimation

A collection of Sesbania sesban accessions was grown out in the field and classified using real and standardised values of 10 agronomic attributes. Clustering the accessions using the observed values of the attributes produced several groups which were mainly based on the dry matter yields after the first and second harvests. The cluster analysis on the standardised values of the descriptors provided 10 similarity groups. These groups were identified and compared with an earlier morphological classification. Some of the observed characters were used to establish their relationship with biomass yield of the trees. The data were therefore subjected to linear regression analysis. Predictive equations were obtained for the logarithmical transformed biomass yield using stem diameter at 30 cm from ground level plus the plant height with r to the square root of 2 values between 84 and 89 percent

EFFECTS OF SAMPLE SIZE RATIO ON THE PERFORMANCE OF THE QUADRATIC DISCRIMINANT FUNCTION

This study investigated the performance of the heteroscedastic discriminant function under the non-optimal condition of unbalanced group representation in the populations. The asymptotic performance of the classification function with respect to increased Mahalanobis’ distance (under this condition) was considered. Results obtained have shown that the misclassification of observations from the smaller group escalates when the sample size ratio 1:2 is exceeded (for small sample sizes). Results also show more sensitivity to sample size than the distance function when the data set is balanced, while the performance of the function in the classification of the underrepresented group improved by increasing the distance function. More robustness with unbalanced data was also observed with the Quadratic Function than the Linear Discriminant Function.       &nbsp

Effects of Sample Size Ratio on the Performance of the Quadratic Discriminant Function

This study investigated the performance of the heteroscedastic discriminant function under the non-optimal condition of unbalanced group representation in the populations. The asymptotic performance of the classification function with respect to increased Mahalanobis’ distance (under this condition) was considered. Results obtained have shown that the misclassification of observations from the smaller group escalates when the sample size ratio 1:2 is exceeded (for small sample sizes). Results also show more sensitivity to sample size than the distance function when the data set is balanced, while the performance of the function in the classification of the underrepresented group improved by increasing the distance function. More robustness with unbalanced data was also observed with the Quadratic Function than the Linear Discriminant Function

Error Rates Stability of The Homoscedastic Discriminant Function

In this study the stability of the observed error rates of the homoscedastic discriminant function relative to the number of parameters in the model using simulated data from multivariate normal populations was investigated.   Three models were considered, the four, six and eight variables models, each having four values of the separator function (). Equal and unequal prior probabilities were considered for the different number of parameter and separator function configurations. The asymptotic performance of the models was considered using the cross validation error rate estimation procedure. Results indicate the six variable models as being more stable (displaying less variability in the estimated error rates) than the other models under consideration. Less deterioration was observed for the six-variable model specification as was evident in the other models and this was more pronounced for smaller values of. &nbsp

A research methodology for characterising dairy product consumption systems

This document on characterisation methodology specifically refers to the dairy consumption systems. The methodology developed and presented herein aims at guiding the activities of scientists who wish to investigate the dairy consumption systems at or around a specific site. Some characterisation of dairy product consumption has been conducted at most ILCA zonal sites. Pursued by different scientists at different times and places, a variety of methodological approaches have been employed in conducting these studies. This document is based upon ILCA's experiences at its zonal sites and incorporates the methodological lessons learned in the course of the studies. The steps that have been followed in constructing the conceptual framework instruments and in specifying the analytical methods are outlined. Data collected and analysed following this format will allow drawing conclusions about a particular location and its consumption system. It will also facilitate planning future research and development activities

Cowpea as a key factor for a new approach to integrated crop–livestock systems research in the dry savannas of West Africa

Agriculture in the dry savannas is intensifying in response to increasing populations of humans and livestock. As a result, increased productivity demands are placed upon integrated crop–livestock systems and more emphasis is on the roles of legumes such as cowpea. Cowpea has the potential to function as a key integrating factor in intensifying systems through supplying protein in the human diet, and fodder for livestock, and bringing nitrogen into the farming system through nitrogen fi xation. This paper describes the development and evaluation of integrated “best-bet” options which maximize the benefi ts of cowpea and addresses aspects of improved crop varieties, crop and livestock management, nutrient cycling, and soil fertility. The approach used includes a multicenter, multidisciplinary approach to working with farmers which combines complementary strengths of previous component research involving crops and livestock by key international and national research institutions in the region