ETD Collection

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    Modelling learner discipline in a public school
    (2016) Ramokgadi, Mabala William
    The study explores the application of statistical methods to determine factors influencing learners to commit offences at school. Focus is on the time taken to commit a second offence and the number of repeat offences committed by learners after the first offence. The survival time from the first offence to a second offence is analysed by using Kaplan-Meier estimate of the survival function, the tests for equality of survivor functions, the Cox proportional hazards model, and the parametric hazards models. The number of repeat offences is analysed by fitting the Poisson regression model and Negative Binomial regression model. As many learners are expected not to offend again, the Zero Inflated Poisson (ZIP) model is also fitted to determine which factors influence learners not to commit a repeat offence. Factors that are related to the school environment were used in the study of learner offence. The categorical variables are learner grade (class), gender, home location, parental involvement, repeating a grade, suspected substance abuse, and hostel residence. The learner performance in the three selected subjects were used as continuous variables. The results of the analysis should also assist the schools in assessing the effectiveness of other forms of punishment since corporal punishment was abolished.
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    Peri-operative deaths in two major academic hospitals in Johannesburg, South Africa
    (2012-07-11) Lungren, Aina Christina
    Background to and purpose of the study An adverse outcome during the administration of an anaesthetic may result in morbidity or mortality, the latter providing us with the most fundamental measure of the safety of anaesthesia for our patients. Peri-operative deaths due to anaesthesia have not been documented in the province of Gauteng, South Africa, since 1955. The purpose of this study was to document these deaths and compare the findings with previous South African studies, as well as some studies performed overseas. Aims and objectives This study aimed to investigate and determine the prevalence of anaesthesia associated deaths, particularly those that occurred as a direct result of anaesthesia (ACD), both general and regional in two major academic hospitals in the Johannesburg area. These were the Charlotte Maxeke Johannesburg Academic Hospital and the Chris Hani Baragwanath Maternity Hospital. The objectives included examining current legislation and the interpretation thereof with recommendations, as well as the causes or possible risk factors involved in the peri-operative deaths that were studied. vii Research methods and procedures This was a retrospective longitudinal descriptive study, in the form of a clinical audit. All peri-operative deaths during the period 2000 to 2004 were studied at both sites. Numerous data were collected from each death, and descriptive and analytical statistics performed using SAS for Windows to provide frequencies for all of the variables recorded, with subsequent categorical analysis. Results The Anaesthetic Contributory Death (ACD) rate at the Charlotte Maxeke Johannesburg Academic Hospital (CMJAH) was 0.4 per 10,000, which is an improvement from the pilot study that was conducted in that hospital during 1999, but it is still higher per 10,000 than the figures from the United Kingdom. The Anaesthetic Contributory Maternal Death (ACDM) rate at the Chris Hani Baragwanath Hospital was similar to the ACD rate at the CMJAH, and similar to the rate in the United Kingdom. Conclusions The ACD rate in these two hospitals is low, and may well not improve any further, as human error cannot totally be eliminated from anaesthetic practice. The South African law does not specify a time period from the start of the anaesthetic during which a peri-operative death is classified as an ACD. This is poorly understood by the medical fraternity and general public.
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    Assessing the usefulness of sample survey designs and census data with respect to poverty mapping in Ethiopia
    (2008-06-27T11:40:27Z) Gebretsadik, Alemayehu
    We investigated the effect of different probability sampling designs (simple random sampling, stratified, cluster and systematic sampling designs) on estimates of age, gender proportions, and proportions of the population with different education levels, and access to water. To investigate the effect of the sample designs we used as a sampling frame the census 1994 data obtained from Central Statistical Agency of Ethiopia (CSA). In order to compare results obtained from different sampling designs, estimates of population means and proportions for selected variables at household levels using 1, 5 and 10% sample size is considered. The performance of these sampling techniques is observed on the following dimensions: relative accuracy, standard error, confidence intervals, precision and also we compared the effect of the different methods of calculating variances like Taylor series and jack-knife, the comparison of this two methods is done by drawing 100 different samples of 1% for stratified and cluster sampling. It was found that in general the relative accuracy for the selected variable obtained from the stratified sampling design is better than other estimates. We also find evidence that the 95% confidence interval constructed for each method contains the true population value, but the confidence interval for cluster sample is wider than the others that indicate less precision than others. The result of the comparison of the different methods of estimating the variance from the simulated population variance indicates that, for cluster sampling, both of the Taylor linearization and jack-knife methods tend to overestimate the population variance, whereas for stratified sampling the population standard error is in between of the standard error of the both methods indicating when one underestimates the other overestimates. Design effects were also compared, and it was found that the design effect for cluster sampling was larger that for the other methods, as expected. Survey cost information is needed to further inform discussion of the usefulness of the different methods. We assessed the extent of poverty by calculating the poverty index for the Tigray region. To calculate the poverty index we used the method proposed by the United Nations Development Programme (UNDP). Using the Welfare/Poverty Monitoring Survey year 2000 (WMS2000) data obtained from CSA, we found that the region is highly affected by each of the dimensions investigated. Further questions need to be added to questionnaires in order to allow use of the census data in calculating poverty maps.