Online vs. face-to-face discussions in a web-based research methods course for postgraduate nursing students : A quasi-experimental study

Background: Web-based technologies are increasingly being used to create modes of online learning for nurses but their effect has not been assessed in nurse education. Objectives: Assess whether participation in face-to-face discussion seminars or online asynchronous discussion groups had different effects on educational attainment in a webbased course. Design: Non-randomised or quasi-experimental design with two groups – students choosing to have face-to-face discussion seminars and students choosing to have online discussions. Setting: The Core Methods module of a postgraduate research methods course. Participants: All 114 students participating in the first 2 years during which the course teaching material was delivered online. Outcome: Assignment mark for Core Methods course module. Methods: Background details of the students, their choices of modules and assignment marks were collected as part of the routine course administration. Students’ online activities were identified using the student tracking facility within WebCT. Regression models were fitted to explore the association between available explanatory variables and assignment mark. Results: Students choosing online discussions had a higher Core Methods assignment mark (mean 60.8/100) than students choosing face-to-face discussions (54.4); the difference was statistically significant (t = 3.13, df = 102, p = 0.002), although this ignores confounding variables. Among online discussion students, assignment mark was significantly correlated with the numbers of discussion messages read (Kendall’s taub = 0.22, p = 0.050) and posted (Kendall’s taub = 0.27, p = 0.017); among face-to-face discussion students, it was significantly associated with the number of non-discussion hits in WebCT (Kendall’s taub = 0.19, p = 0.036). In regression analysis, choice of discussion method, whether an MPhil/PhD student, number of non-discussion hits in WebCT, number of online discussion messages read and number posted were associated with assignment mark at the 5% level of significance when taken singly; in combination, only whether an MPhil/PhD student (p = 0.024) and number of non-discussion hits (p = 0.045) retained significance. Conclusions: This study demonstrates that a research methods course can be delivered to postgraduate healthcare students at least as successfully by an entirely online method in which students participate in online discussion as by a blended method in which students accessing web-based teaching material attend face-to-face seminar discussions. Increased online activity was associated with higher assignment marks. The study highlights new opportunities for educational research that arise from the use of virtual learning environments that routinely record the activities of learners and tutors

Truthful Facility Assignment with Resource Augmentation: An Exact Analysis of Serial Dictatorship

We study the truthful facility assignment problem, where a set of agents with private most-preferred points on a metric space are assigned to facilities that lie on the metric space, under capacity constraints on the facilities. The goal is to produce such an assignment that minimizes the social cost, i.e., the total distance between the most-preferred points of the agents and their corresponding facilities in the assignment, under the constraint of truthfulness, which ensures that agents do not misreport their most-preferred points. We propose a resource augmentation framework, where a truthful mechanism is evaluated by its worst-case performance on an instance with enhanced facility capacities against the optimal mechanism on the same instance with the original capacities. We study a very well-known mechanism, Serial Dictatorship, and provide an exact analysis of its performance. Although Serial Dictatorship is a purely combinatorial mechanism, our analysis uses linear programming; a linear program expresses its greedy nature as well as the structure of the input, and finds the input instance that enforces the mechanism have its worst-case performance. Bounding the objective of the linear program using duality arguments allows us to compute tight bounds on the approximation ratio. Among other results, we prove that Serial Dictatorship has approximation ratio $g/(g-2)$ when the capacities are multiplied by any integer $g \geq 3$. Our results suggest that even a limited augmentation of the resources can have wondrous effects on the performance of the mechanism and in particular, the approximation ratio goes to 1 as the augmentation factor becomes large. We complement our results with bounds on the approximation ratio of Random Serial Dictatorship, the randomized version of Serial Dictatorship, when there is no resource augmentation

Competitive Analysis for Two Variants of Online Metric Matching Problem

In this paper, we study two variants of the online metric matching problem. The first problem is the online metric matching problem where all the servers are placed at one of two positions in the metric space. We show that a simple greedy algorithm achieves the competitive ratio of 3 and give a matching lower bound. The second problem is the online facility assignment problem on a line, where servers have capacities, servers and requests are placed on 1-dimensional line, and the distances between any two consecutive servers are the same. We show lower bounds $1+ \sqrt{6}$ $(> 3.44948)$, $\frac{4+\sqrt{73}}{3}$ $(>4.18133)$ and $\frac{13}{3}$ $(>4.33333)$ on the competitive ratio when the numbers of servers are 3, 4 and 5, respectively.Comment: 12 pages. Update from the 1st version: The first author was added and Theorems 3, 4 and 5 were improve

Online Mixed Packing and Covering

In many problems, the inputs arrive over time, and must be dealt with irrevocably when they arrive. Such problems are online problems. A common method of solving online problems is to first solve the corresponding linear program, and then round the fractional solution online to obtain an integral solution. We give algorithms for solving linear programs with mixed packing and covering constraints online. We first consider mixed packing and covering linear programs, where packing constraints are given offline and covering constraints are received online. The objective is to minimize the maximum multiplicative factor by which any packing constraint is violated, while satisfying the covering constraints. No prior sublinear competitive algorithms are known for this problem. We give the first such --- a polylogarithmic-competitive algorithm for solving mixed packing and covering linear programs online. We also show a nearly tight lower bound. Our techniques for the upper bound use an exponential penalty function in conjunction with multiplicative updates. While exponential penalty functions are used previously to solve linear programs offline approximately, offline algorithms know the constraints beforehand and can optimize greedily. In contrast, when constraints arrive online, updates need to be more complex. We apply our techniques to solve two online fixed-charge problems with congestion. These problems are motivated by applications in machine scheduling and facility location. The linear program for these problems is more complicated than mixed packing and covering, and presents unique challenges. We show that our techniques combined with a randomized rounding procedure give polylogarithmic-competitive integral solutions. These problems generalize online set-cover, for which there is a polylogarithmic lower bound. Hence, our results are close to tight

A Lower Bound on the Competitive Ratio of the Permutation Algorithm for Online Facility Assignment on a Line

In the online facility assignment on a line (OFAL) with a set $S$ of $k$ servers and a capacity $c:S\to\mathbb{N}$, each server $s\in S$ with a capacity $c(s)$ is placed on a line and a request arrives on a line one-by-one. The task of an online algorithm is to irrevocably assign a current request to one of the servers with vacancies before the next request arrives. An algorithm can assign up to $c(s)$ requests to each server $s\in S$. In this paper, we show that the competitive ratio of the permutation algorithm is at least $k+1$ for OFAL where the servers are evenly placed on a line. This disproves the result that the permutation algorithm is $k$-competitive by Ahmed et al..Comment: 5 page

Investigating design features of a computer-mediated communication system

Computer-mediated communication (CMC) is increasingly used in higher education, but it is not without problems. The effectiveness of CMC depends on many factors, including the characteristics of CMC systems themselves. The research reported here therefore aimed to investigate how an educational CMC system might be improved, in order to support learning more effectively. The main context for the research was distance learning at the UK Open University (OU). A two-stage, mixed methods research approach was adopted. In the first stage, interviews and observations were carried out to explore the benefits and problems experienced by users. This revealed two major issues: information overload and lack of social presence. Information overload relates to users’ problems dealing with large numbers of messages. Social presence relates to the need for users to feel connected with each other. The second stage investigated system features aimed at addressing these issues, implemented in a prototype computer conferencing system. Features to address overload included branched message threading and user recommendations. Features to address social presence were ‘résumés’ and instant messaging. These features were evaluated using questionnaires, with several cohorts of students in an OU course. Students expressed approval of the features, although some features were not widely used. Students preferred branched threading to chronological threading because branching helped them to follow ‘conversations’. Students were uncomfortable recommending messages, feeling that the value of a message would vary between people. They were also uncomfortable using instant messaging to contact others whom they did not know. However, the awareness aspect of instant messaging provided a sense of solidarity. The research demonstrated that the problems of overload and lack of social presence are significant, and each has social aspects which must be addressed. Students’ relationships with each other affect whether and how they use the features of CMC systems. We can conclude that particular attention must be paid to the social aspects of online communication, both when designing educational CMC systems and when considering how they are used. To maximise the benefits for learning, students need to feel comfortable with each other online, and there are few short cuts to achieving this