title: Efficient online evaluation of big data stream classifiers

authors: Bifet, Albert

subjects: Data Streams

abstract: The evaluation of classifiers in data streams is fundamental so that poorly-performing models can be identified, and either improved or replaced by better-performing models. This is an increasingly relevant and important task as stream data is generated from more sources, in real-time, in large quantities, and is now considered the largest source of big data. Both researchers and practitioners need to be able to effectively evaluate the performance of the methods they employ. However, there are major challenges for evaluation in a stream. Instances arriving in a data stream are usually time-dependent, and the underlying concept that they represent may evolve over time. Furthermore, the massive quantity of data also tends to exacerbate issues such as class imbalance. Current frameworks for evaluating streaming and online algorithms are able to give predictions in real-time, but as they use a prequential setting, they build only one model, and are thus not able to compute the statistical significance of results in real-time. In this paper we propose a new evaluation methodology for big data streams. This methodology addresses unbalanced data streams, data where change occurs on different time scales, and the question of how to split the data between training and testing, over multiple models.

text: Efficient online evaluation of big data stream classifiers The evaluation of classifiers in data streams is fundamental so that poorly-performing models can be identified, and either improved or replaced by better-performing models. This is an increasingly relevant and important task as stream data is generated from more sources, in real-time, in large quantities, and is now considered the largest source of big data. Both researchers and practitioners need to be able to effectively evaluate the performance of the methods they employ. However, there are major challenges for evaluation in a stream. Instances arriving in a data stream are usually time-dependent, and the underlying concept that they represent may evolve over time. Furthermore, the massive quantity of data also tends to exacerbate issues such as class imbalance. Current frameworks for evaluating streaming and online algorithms are able to give predictions in real-time, but as they use a prequential setting, they build only one model, and are thus not able to compute the statistical significance of results in real-time. In this paper we propose a new evaluation methodology for big data streams. This methodology addresses unbalanced data streams, data where change occurs on different time scales, and the question of how to split the data between training and testing, over multiple models.

year: 2015

title: Use of video shadow for small group interaction awareness on a large interactive display surface

authors: Apperley, Mark

subjects: computer science

abstract: This paper reports work done as part of the Large Interactive Display Surface (LIDS) project at the University of Waikato.  One application of the LIDS equipment is distributed meeting support.  In this context large display surfaces are used as shared workspaces by people at collaborating sites.  A meeting with start with a shared presentation document, typically and agenda document with summary and detail on agenda items as required.  During the meeting, annotations with be made on the shared document, and new pages will be added with notes and drawings. 
To prevent access collisions and generally mediate use of the shared space, mechanisms to provide awareness of actions of people at other sites are required.  In our system a web camera is used to capture a low-resolution image of the person/people near the board on each side.  Rather than transmit the image directly we computed a shadow/silhouette.  The shadow is displayed behind other screen content.  This provides awareness of position and impending write actions and allows intentional pointing to locations of the screen.  It also has the advantage of being transmitted with low bandwidth, being relatively insensitive to low frame rates, and minimizing visual interference with substantive data being displayed on the screen.

text: Use of video shadow for small group interaction awareness on a large interactive display surface This paper reports work done as part of the Large Interactive Display Surface (LIDS) project at the University of Waikato.  One application of the LIDS equipment is distributed meeting support.  In this context large display surfaces are used as shared workspaces by people at collaborating sites.  A meeting with start with a shared presentation document, typically and agenda document with summary and detail on agenda items as required.  During the meeting, annotations with be made on the shared document, and new pages will be added with notes and drawings. 
To prevent access collisions and generally mediate use of the shared space, mechanisms to provide awareness of actions of people at other sites are required.  In our system a web camera is used to capture a low-resolution image of the person/people near the board on each side.  Rather than transmit the image directly we computed a shadow/silhouette.  The shadow is displayed behind other screen content.  This provides awareness of position and impending write actions and allows intentional pointing to locations of the screen.  It also has the advantage of being transmitted with low bandwidth, being relatively insensitive to low frame rates, and minimizing visual interference with substantive data being displayed on the screen.

year: 2002-07

title: Are they really at risk? Students' stories of success.

authors: Gray, Sheridan

subjects: Student engagement

abstract: In 2011, as the year level dean for year 13, I was surprised and pleased to see a group of students complete their fifth year of secondary schooling, contrary to teacher expectations, and in spite of earlier signs of disengagement and struggle.  Such students are frequently labelled “at risk” in our secondary schools. Truancy, lack of achievement, conduct issues, learning difficulties and health problems are seen as indicators of an at risk student by teachers. 

Statistically in Aotearoa, Māori and Pasifika students and students from low socio-economic families tend to be overrepresented among disengaged or early leavers from secondary schools, and so being from these cultures, and being from a low socio-economic group becomes a “risk” factor.   This can lead to assumptions among teachers about the students’ families, how parents value education, and even about the capacity of these groups to be able to succeed in education.  A range of strategies and programmes have been implemented in an attempt to address these issues, including Te Kotahitanga, Ka Hikitia and the Pasifika Education Plan, Resource Teachers Learning and Behaviour, Restorative Practice, and more recently Positive Behaviour for Learning

While there has been a shift in such approaches from deficit of students to emphasising more positive attitudes in teachers, the perspectives of the students themselves are missing from the discussion about these issues.  This study asks students what factors helped them to stay, and to achieve at least a level one NCEA qualification

The findings show that retention and engagement of “at risk” students requires careful attention to the quality of relationships across the school community: students, teachers and parents. They discredit some commonly held assumptions that “at risk” students and their parents do not value education and that teachers cannot support these students sufficiently. These quality relationships are respectful, responsive and tenacious showing a high level of respect for and interest in the students that goes beyond a teaching and learning relationship.  It also suggests that the discourse of “risk” invites a disrespectful response to retention and engagement of students.

text: Are they really at risk? Students' stories of success. In 2011, as the year level dean for year 13, I was surprised and pleased to see a group of students complete their fifth year of secondary schooling, contrary to teacher expectations, and in spite of earlier signs of disengagement and struggle.  Such students are frequently labelled “at risk” in our secondary schools. Truancy, lack of achievement, conduct issues, learning difficulties and health problems are seen as indicators of an at risk student by teachers. 

Statistically in Aotearoa, Māori and Pasifika students and students from low socio-economic families tend to be overrepresented among disengaged or early leavers from secondary schools, and so being from these cultures, and being from a low socio-economic group becomes a “risk” factor.   This can lead to assumptions among teachers about the students’ families, how parents value education, and even about the capacity of these groups to be able to succeed in education.  A range of strategies and programmes have been implemented in an attempt to address these issues, including Te Kotahitanga, Ka Hikitia and the Pasifika Education Plan, Resource Teachers Learning and Behaviour, Restorative Practice, and more recently Positive Behaviour for Learning

While there has been a shift in such approaches from deficit of students to emphasising more positive attitudes in teachers, the perspectives of the students themselves are missing from the discussion about these issues.  This study asks students what factors helped them to stay, and to achieve at least a level one NCEA qualification

The findings show that retention and engagement of “at risk” students requires careful attention to the quality of relationships across the school community: students, teachers and parents. They discredit some commonly held assumptions that “at risk” students and their parents do not value education and that teachers cannot support these students sufficiently. These quality relationships are respectful, responsive and tenacious showing a high level of respect for and interest in the students that goes beyond a teaching and learning relationship.  It also suggests that the discourse of “risk” invites a disrespectful response to retention and engagement of students.

year: 2012