Numerical Methods for Mathematical Models on Warrant Pricing

>Magister Scientiae - MScWarrant pricing has become very crucial in the present market scenario. See, for example, M. Hanke and K. Potzelberger, Consistent pricing of warrants and traded options, Review Financial Economics 11(1) (2002) 63-77 where the authors indicate that warrants issuance affects the stock price process of the issuing company. This change in the stock price process leads to subsequent changes in the prices of options written on the issuing company's stocks. Another notable work is W.G. Zhang, W.L. Xiao and C.X. He, Equity warrant pricing model under Fractional Brownian motion and an empirical study, Expert System with Applications 36(2) (2009) 3056-3065 where the authors construct equity warrants pricing model under Fractional Brownian motion and deduce the European options pricing formula with a simple method. We study this paper in details in this mini-thesis. We also study some of the mathematical models on warrant pricing using the Black-Scholes framework. The relationship between the price of the warrants and the price of the call accounts for the dilution effect is also studied mathematically. Finally we do some numerical simulations to derive the value of warrants

Manufacturing homemade alcohol in the City of Tshwane, South Africa

This study aimed to determine the prevalence of home-based manufacturing of alcoholic beverages in townships/peri-urban households and to examine whether certain characteristics (such as household, demographics and drinking behaviour of participants who reported brewing of alcohol in their homes) predicted home brewing of alcohol. The study utilized data from South African arm of International Alcohol Control study conducted in the city of Tshwane. A household survey used multi-stage stratified cluster random sampling. Homemade alcohol was defined as participants who reported home-based alcohol brewing at their homes. Stata Version 14.0 was used for analyses. Nine percent of the sample reported brewing of alcohol in their households. Race, employment of the main income earners and number of eligible members in the household have predicted homebased alcohol brewing. The study raised important questions about the prevalence of home brewing of alcohol in the city of Tshwane as it might be a common practice in other cities. Keywords: Homemade alcohol, alcohol brewing, South Afric

A cross-sectional investigation of softening indicators among South African smokers : results from the South African Social Attitudes Survey between 2007 and 2018

DATA AVAILABILITY STATEMENT : Data are available on reasonable request. Requests will be considered on a case-by-case basis.Recent studies have shown softening among smokers in different countries and in different population groups i.e., as smoking prevalence declined remaining smokers made more quit attempts and smoked fewer cigarettes per day (CPD), as opposed to hardening. We examined tobacco use-related cross-sectional data from five waves of the South African Social Attitudes Survey (SASAS 2007–2018, N = 14,822). Accounting for the SASAS’s complex survey design, we ran logistic and linear regressions for smoking prevalence, and for the following indicators of softening: plans to quit smoking within a month, time to first cigarette (5 min, TTFC) and cigarettes smoked per day (CPD). We controlled for survey wave, age, sex, race, marital status, educational level and urban/rural residence. Smoking prevalence remained stable from 2007 (20.7%) to 2018 (22.2%) in the overall population of smokers (p = 0.197), and within sex and race group of smokers. In the adjusted model, there was a significant decline in CPD over time, 0.12 cigarettes per year. There was also a significant decrease in TTFC among males over time. Among women, CPD declined significantly by 0.32 cigarettes per year. The proportion of Asians/Indians planning to quit also decreased over time. South African smokers do not consistently show significant change in the softening indicators overall. Stronger tobacco control policies and better-tailored smoking cessation interventions are needed to achieve a significant decrease in smoking prevalence across sex and other subpopulations in South Africa.The African Capacity Building Foundation were funded by the South African Medical Research Council.https://www.elsevier.com/locate/pmedrhj2023School of Health Systems and Public Health (SHSPH

Characteristics and predictors of Heavy Episodic Drinking (HED) among young people aged 16–25 : the International Alcohol Control Study (IAC), Tshwane, South Africa

CITATION: Harker, N. et al. Characteristics and predictors of Heavy Episodic Drinking (HED) among young people aged 16–25: The International Alcohol Control Study (IAC), Tshwane, South Africa. International Journal of Environmental Research and Public Health, 17(10). doi:10.3390/ijerph17103537The original publication is available at https://www.mdpi.com/journal/ijerphIn South Africa, little is known about alcohol consumption patterns, such as drinks consumed, container size, salience of alcohol price, affordability and availability, and perceptions of alcohol policies as potential predictors of heavy episodic alcohol (HED) use among young people. This paper examines predictors of HED among young people with specific consideration given to these alcohol consumption patterns. This study conducted in the Tshwane Metropole in 2014 employed multi-stage stratified cluster random sampling. Participants were between the ages 16–25 years. A structured questionnaire was used to collect data. Of the 287 (n = 678) participants who had used alcohol in the past six months and for whom we had complete consumption data, almost half were identified as heavy episodic drinkers (HEDs) and were significantly more likely to consume alcohol on a daily basis (p = 0.001). Having nightclub as the primary drinking location (p = 0.023) and drinking from a container size bigger than one standard drink (p = 0.014) were significant predictors for HED. HEDs were also more likely to have a perception that most people consume alcohol (p = 0.047). The results point to HED of alcohol among young people who drink in South Africa, highlighting the need for multicomponent interventions.https://www.mdpi.com/1660-4601/17/10/3537Publishers versio

Did COVID-19-Related Alcohol Sales Restrictions Reduce Alcohol Consumption? Findings from a National Online Survey in South Africa

Background: South Africa has a high prevalence of heavy episodic drinking (HED). Due to the high levels of alcohol misuse and violence, public hospital intensive care units were often overrun during the COVID-19 pandemic. This research investigated alcohol intake behaviour change during differing levels of lockdown restrictions, which included bans on alcohol sales. Methods: A self-reported Facebook survey ran from July to November 2020. The questions included socio-demographics, income, alcohol intake, purchasing behaviour, and reasoning. Chi-square tests/Fisher’s exact test for categorical data, Student’s t-test for normal continuous data, and the Mann–Whitney U test for non-normal data were applied. Multiple logistic regression was run for HED versus moderate drinkers. Results: A total of 798 participants took part in the survey, of which 68.4% were female. Nearly 50% of participants fell into the HED category and the majority bought alcohol illegally during restrictions. HED respondents who drank more alcohol than usual during restrictions reported that they felt stressed, needed to relax, and were bored. Conclusions: Policies intended to increase the pricing of alcohol may have the potential to reduce alcohol intake. Reducing stress and anxiety may be key to curtailing HED during emergency situations

Tobacco use and nicotine dependence among people living with HIV who drink heavily in South Africa: a cross-sectional baseline study

Abstract

Tobacco use and behaviour among South African adolescents and young adults: systematic review and meta-analysis

Objective Tobacco use, particularly the initiation of smoking during adolescence and young adulthood, represents a significant public health concern in South Africa. This study aims to conduct a comprehensive review of published literature about tobacco use and behaviour among adolescents and young adults and to determine an aggregated prevalence estimate of tobacco use within this demographic.Design Systematic review and meta-analysis.Data sources PubMed/MEDLINE, EMBASE, Cochrane Library, Scopus and Google Scholar were searched from 1 January 2000 through 31 October 2023.Eligibility criteria Studies were eligible for inclusion if they were cross-sectional studies conducted in South Africa and measured the prevalence and determinants of tobacco use among adolescents and young adults aged 12–24 years.Data extraction and synthesis Two reviewers independently extracted information for each article and saved it into an Excel spreadsheet. Risk of bias analysis was conducted using the Risk of Bias Assessment Tool for non-randomised studies. The methodology quality of each selected study was evaluated using the Joanna Briggs Institute checklist. The heterogeneity of prevalence estimates was assessed using I2 statistic (random-effects DerSimonian-Laid approach).Results Out of 73 articles identified, 12 articles were included in the analysis. The pooled prevalence of current tobacco use among South African adolescents and young adults was estimated to be 22%. The pooled prevalence of tobacco use among school dropouts, university students and secondary school learners was 51%, 20% and 16%, respectively. Stratifying using gender, boys (26%) were two times more likely to use tobacco than girls (13%).Conclusion The elevated occurrence of tobacco usage among South African adolescents and young adults is a relevant public health concern. There is a need for more population-based prevalence studies at a national level to estimate the burden of tobacco use in South Africa.PROSPERO registration number CRD42023428369

Non-Smoker’s Exposure to Second-Hand Smoke in South Africa during 2017

Current South African tobacco control law allows for 25% designated smoking areas in some indoor public places. This study investigates non-smokers’ exposure to second-hand smoke (SHS) in workplaces, homes, cafés/restaurants, and shebeens (local bars) using data from the 2017 South African Social Attitude Survey. Factors associated with any level of exposure were explored using multiple-variable-adjusted logistic regression analysis. The sample of 3063 participants (16+ years old), comprised 51.7% females and 78.5% Black Africans. The current smoking prevalence from this study was 21.5%. About 47% of non-smokers reported exposure to SHS in at least one location. Females were significantly less likely to be exposed to SHS in all locations except at home compared to males. Adjusted logistic regression analysis showed that females, adults aged 45–54 years, 55–64 years, and 65+ years were significantly less likely to be exposed to SHS (adjusted odds ratio (AOR) = 0.63, 0.60, 0.55, and 0.24, respectively) than males and those aged 16–24 years. Those who identified as Coloureds were significantly more likely to be exposed to SHS (AOR = 1.69) than Black Africans. This study found that nearly half of non-smokers reported exposure to SHS. A 100% smoke-free policy consistent with the World Health Organisation (WHO) Framework Convention on Tobacco Control would protect more people from exposure to SHS in South Africa

Alcohol consumption patterns, suppliers and online alcohol marketing: Before and during COVID-19 alcohol bans

COVID-19-related alcohol sales bans and stay-at-home orders prompted the alcohol industry in South Africa to increase their online alcohol sales promotions. We investigated changes in alcohol-related behaviour and the drivers of illegal alcohol sales through a self-reported Facebook survey that ran from July to November 2020. Questions included socio-demographics and comparison of alcohol purchasing behaviour and intake during 2019 and 2020. Statistical tests were applied to find associations between illegal alcohol purchasing and alcohol-related behaviours. A total of 792 participants took part in the survey, 69.7% of whom were female. During lockdown periods, most participants (55.3%) bought alcohol illegally from illegal outlets or friends. Online alcohol-delivery marketing increased by 20 percentage points from 2019 to 2020, with participants stating that they saw a lot of advertisements per day and 80% of persons under 25 years were not asked to verify their age in 2020 upon delivery. Home-brewed beer and vodka intake increased in 2020 during the alcohol sales bans. Men from the Western Cape who engaged in daily or weekly heavy episodic drinking were more prone to purchase alcohol illegally. The Western Cape, which is South Africa’s most prolific wine-producing region, had the highest odds of people buying alcohol illegally, with wine being found to be the most frequently bought alcohol online and consumed by these participants. There is a need for further research into the differences in alcohol-related behaviour affecting illegal alcohol purchasing according to income group, proximity to alcohol producers and underage alcohol sales and marketing through online applications. Significance: Alcohol sales bans have the potential to reduce and stop the alcohol intake of moderate drinkers, but may make heavy episodic drinkers drink more than usual. During COVID-19 lockdown, illegal alcohol sales were taking place through unlicenced alcohol outlets and friends, and not through licenced online applications. Unlicenced alcohol outlets need to be addressed to prevent future illegal alcohol sales. Stricter regulations aimed at legal online alcohol sales applications should be put in place to prevent alcohol sales to minors and those who have already consumed too much alcohol. There should be a ban on marketing of addictive substances, such as alcohol

Self-reported alcohol use versus phosphatidylethanol in behavioral trials: A study of people living with HIV in Tshwane, South Africa.

BACKGROUND: Accurately quantifying alcohol use among persons with HIV (PWH) is important for validly assessing the efficacy of alcohol reduction interventions. METHODS: We used data from a randomized controlled trial of an intervention to reduce alcohol use among PWH who were receiving antiretroviral therapy in Tshwane, South Africa. We calculated agreement between self-reported hazardous alcohol use measured by the Alcohol Use Disorders Identification Test (AUDIT; score ≥8) and AUDIT-Consumption (AUDIT-C; score ≥3 for females and ≥4 for males), heavy episodic drinking (HED) in the past 30 days, and heavy drinking in the past 7 days with a gold standard biomarker--phosphatidylethanol (PEth) level (≥50 ng/mL)--among 309 participants. We used multiple logistic regression to assess whether underreporting of hazardous drinking (AUDIT-C vs. PEth) differed by sex, study arm, and assessment time point. RESULTS: Participants mean age was 40.6 years, 43% were males, and 48% were in the intervention arm. At 6 months, 51% had PEth ≥50 ng/mL, 38% and 76% had scores indicative of hazardous drinking on the AUDIT and AUDIT-C, respectively, 11% reported past 30-day HED, and 13% reported past 7-day heavy drinking. At 6 months, there was low agreement between AUDIT-C scores and past 7-day heavy drinking relative to PEth ≥50 (sensitivities of 83% and 20% and negative predictive values of 62% and 51%, respectively). Underreporting of hazardous drinking at 6 months was associated with sex (OR = 3.504. 95% CI: 1.080 to 11.364), with odds of underreporting being greater for females. CONCLUSIONS: Steps should be taken to decrease underreporting of alcohol use in clinical trials