On association in regression: the coefficient of determination revisited

Universal coefficients of determination are investigated which quantify the strength of the relation between a vector of dependent variables Y and a vector of independent covariates X. They are defined as measures of dependence between Y and X through theta(x), with theta(x) parameterizing the conditional distribution of Y given X=x. If theta(x) involves unknown coefficients gamma the definition is conditional on gamma, and in practice gamma, respectively the coefficient of determination has to be estimated. The estimates of quantities we propose generalize R^2 in classical linear regression and are also related to other definitions previously suggested. Our definitions apply to generalized regression models with arbitrary link functions as well as multivariate and nonparametric regression. The definition and use of the proposed coefficients of determination is illustrated for several regression problems with simulated and real data sets

Nitrogen removal during summer and winter in a primary facultative WSP pond: preliminary findings from 15N-labelled ammonium tracking techniques

Nitrogen removal mechanisms and pathways within WSP have been the focus of much research over the last 30 years. Debates and theories postulated continue to refine our knowledge regarding the cycling and removal pathways for this important nutrient, but a succinct answer has yet to be provided for holistic nitrogen removal. In this study, two experimental runs using labelled 15N as a stable isotope tracking technique were conducted on a pilot-scale primary facultative WSP in the UK; one in the summer of 2006, and the other in the winter of 2007. An ammonium chloride (15NH4Cl) spike was prepared as the slug for each experimental run, which also contained rhodamine WT to act as a dye tracer enabling the hydraulic characteristics of the pond to be mapped. Initial results from the study are reported here, and findings are compared and contrasted. Preliminary findings reveal that a greater proportion of 15N is incorporated into the algal biomass by assimilation and subsequent release as soluble organic nitrogen in summer than in winter. 15N ammonium passes out of the system much sooner and in a much higher proportion in the winter than in summer

Anarchic Love

In 1997, Ellen Fein and Sherrie Schneider wrote a book titled The Rules.... Rule 3 states, “Don’t Stare or Talk Too Much.” Rule 5—“Don’t Call Him and Rarely Return His Phone Calls.” Rule 33 claims, “Do The Rules and You’ll Live Happily Ever After!” Correct me if I’m wrong, but I believe Cinderella found her happily ever after without The Rules

Mediating identity, 'mobile-ising' culture : the social impact of MXIt in the relational lives of teens

The primary aim of the study was to examine the mediating role that MXit plays in the identity formation of 16-18 year old adolescents. Little is known about the social impact of MXit on adolescents’ identities when this usage is so deeply embedded in the relational exchanges of teens’ everyday experiences. Nine focus groups, four group interviews and two one on one interviews were employed across six schools located in four socioeconomically divergent Cape Town suburbs demarcated using middle to upper-income (Milnerton and Newlands) and lower-income (Khayelitsha and Cloetesville) operational definitions

A comparative study of three ICT network programs using usability testing

Thesis (M. Tech. (Information Technology)) -- Central University of technology, Free State, 2013This study compared the usability of three Information and Communication Technology (ICT) network programs in a learning environment. The researcher wanted to establish which program was most adequate from a usability perspective among second-year Information Technology (IT) students at the Central University of Technology (CUT), Free State. The Software Usability Measurement Inventory (SUMI) testing technique can measure software quality from a user perspective. The technique is supported by an extensive reference database to measure a software product’s quality in use and is embedded in an effective analysis and reporting tool called SUMI scorer (SUMISCO). SUMI was applied in a controlled laboratory environment where second-year IT students of the CUT, utilized SUMI as part of their networking subject, System Software 1 (SPG1), to evaluate each of the three ICT network programs. The results, strengths and weaknesses, as well as usability improvements, as identified by SUMISCO, are discussed to determine the best ICT network program from a usability perspective according to SPG1 students

Time to Turn Up the Volume

I remember my first self-organised donor panel well. It was at the Global Social Change Philanthropy Conference in Washington, DC in 2013. I had just started work as the first coordinator of the Red Umbrella Fund—the newly established fund for and by sex workers. I organised a session that would clarify the distinction between sex work and human trafficking and emphasise the need to fund sex worker organising. We had a strong panel: an awesome sex worker activist, a knowledgeable academic, a passionate service provider, and a committed funder. I was, however, in for a rude awakening: even though the line-up was great, the audience was scarce. I thought to myself, if we can’t even get funders to show up and learn about sex workers’ rights, how will we ever meet the needs of sex worker organisations fighting for their basic human rights