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Chapter XIII: Emerging Missing DataEstim... > EXPERIMENTAL EVALUATION - Pg. 290

0 Marwala 1. 2. The entire data set is categorized at the start of the program. This way when the program builds a dataset for training in a certain category it does not have to redundantly find the category of every record. The first time a neural network is trained in a category it is stored in a multi-dimensional array. When future data from this category needs to be imputed, instead of retraining a network, the stored one is used. This way two networks in the same category are never trained as this would be redundant and networks for categories that never require imputations are not trained as would be the case if the training was done during initialization. EXPERIMENTAL EVALUATION Data and Analysis The data used in this test are obtained from the South African antenatal sero-prevalence survey of 2001. The data for this survey are obtained from questionnaires answered by pregnant women visiting selected public clinics in South Africa. Only women participating for the first time in the survey were eligible to answer the questionnaire. Data attributes used in this study are the HIV.status, education.level, gravidity, parity, age, age of the father, population group and region and are described in detail in earlier chapters. The HIV status is