title: Handling numeric attributes in Hoeffding trees

authors: Pfahringer, Bernhard

subjects: computer science

abstract: For conventional machine learning classification algorithms handling numeric attributes is relatively straightforward. Unsupervised and supervised solutions exist that either segment the data into pre-defined bins or sort the data and search for the best split points. Unfortunately, none of these solutions carry over particularly well to a data stream environment. Solutions for data streams have been proposed by several authors but as yet none have been compared empirically. In this paper we investigate a range of methods for multi-class tree-based classification where the handling of numeric attributes takes place as the tree is constructed. To this end, we extend an existing approximation approach, based on simple Gaussian approximation. We then compare this method with four approaches from the literature arriving at eight final algorithm configurations for testing. The solutions cover a range of options from perfectly accurate and memory intensive to highly approximate. All methods are tested using the Hoeffding tree classification algorithm. Surprisingly, the experimental comparison shows that the most approximate methods produce the most accurate trees by allowing for faster tree growth.

text: Handling numeric attributes in Hoeffding trees For conventional machine learning classification algorithms handling numeric attributes is relatively straightforward. Unsupervised and supervised solutions exist that either segment the data into pre-defined bins or sort the data and search for the best split points. Unfortunately, none of these solutions carry over particularly well to a data stream environment. Solutions for data streams have been proposed by several authors but as yet none have been compared empirically. In this paper we investigate a range of methods for multi-class tree-based classification where the handling of numeric attributes takes place as the tree is constructed. To this end, we extend an existing approximation approach, based on simple Gaussian approximation. We then compare this method with four approaches from the literature arriving at eight final algorithm configurations for testing. The solutions cover a range of options from perfectly accurate and memory intensive to highly approximate. All methods are tested using the Hoeffding tree classification algorithm. Surprisingly, the experimental comparison shows that the most approximate methods produce the most accurate trees by allowing for faster tree growth.

year: 2008

title: Updated reliability and normative values for the standing heel-rise test in healthy adults

authors: Hébert-Losier, Kim

subjects: Lower extremity

abstract: Objectives

The heel-rise test is used to assess the strength and endurance of the plantar flexors in everyday clinical practice. However, several factors may affect outcomes, including sex, age, body mass index and activity level. The aims of this study were to revisit the reliability and normative values of this test, and establish normative equations accounting for several factors.

Design

Cross-sectional observational study with test–retest.

Setting

Community.

Participants

Volunteers (n = 566, age 20 to 81 years).

Interventions

Subjects performed single-legged heel rises to fatigue, standing on a 10° incline, once on each leg. A subset of subjects (n = 32) repeated the test 1 week later. Reliability was quantified using intraclass (ICC) correlation coefficients and Bland–Altman plots {mean difference [95% limits of agreement (LOA)]}, whereas the impact of sex, age, body mass index and activity level on the number of heel rises was determined using non-parametric regression models.

Results

The test showed excellent reliability (ICC = 1.0 right leg, 1.0 left leg), with mean between-day differences in the total number of heel-rise repetitions of 0.2 (95% LOA −6.2 to 6.5) and 0.1 (95% LOA −6.1 to 6.2) for right and left legs, respectively. Overall, males completed more repetitions than females (median 24 vs 21). However, older females (age >60 years) outperformed older males. According to the model, younger males with higher activity levels can complete the most heel rises.

Conclusions

The heel-rise test is highly reliable. The regression models herein can be employed by clinicians to evaluate the outcomes of heel-rise tests of individuals against a comparable normative population.

text: Updated reliability and normative values for the standing heel-rise test in healthy adults Objectives

The heel-rise test is used to assess the strength and endurance of the plantar flexors in everyday clinical practice. However, several factors may affect outcomes, including sex, age, body mass index and activity level. The aims of this study were to revisit the reliability and normative values of this test, and establish normative equations accounting for several factors.

Design

Cross-sectional observational study with test–retest.

Setting

Community.

Participants

Volunteers (n = 566, age 20 to 81 years).

Interventions

Subjects performed single-legged heel rises to fatigue, standing on a 10° incline, once on each leg. A subset of subjects (n = 32) repeated the test 1 week later. Reliability was quantified using intraclass (ICC) correlation coefficients and Bland–Altman plots {mean difference [95% limits of agreement (LOA)]}, whereas the impact of sex, age, body mass index and activity level on the number of heel rises was determined using non-parametric regression models.

Results

The test showed excellent reliability (ICC = 1.0 right leg, 1.0 left leg), with mean between-day differences in the total number of heel-rise repetitions of 0.2 (95% LOA −6.2 to 6.5) and 0.1 (95% LOA −6.1 to 6.2) for right and left legs, respectively. Overall, males completed more repetitions than females (median 24 vs 21). However, older females (age >60 years) outperformed older males. According to the model, younger males with higher activity levels can complete the most heel rises.

Conclusions

The heel-rise test is highly reliable. The regression models herein can be employed by clinicians to evaluate the outcomes of heel-rise tests of individuals against a comparable normative population.

year: 2017

title: Safety hubs and partnership policing: Coordination, collaboration and partnership working in Auckland city centre

authors: Tompson, Lisa

subjects: Community Safety

abstract: This report presents key insights from an exploratory study of the Safety Hub initiative that first appeared in the run up to the 2023 Women’s World Cup in Auckland. It highlights the potential and the pitfalls of partnership-based approaches to community safety in Aotearoa New Zealand. The study was based on a series of in-person focus group discussions and semi-structured interviews with key partners and stakeholders including Community Patrols New Zealand (CPNZ) volunteers, NZ Police (Auckland city Beat officers and Liaison staff), Auckland council staff and Ngā Watene Māori (Māori Wardens). Data collection for this study took place over a four-month period from November 2024 through to February 2025, structured around the availability of participants. The study employed a thematic analysis methodology to systematically identify and organise key themes and issues within the qualitative data gathered from interviews and focus groups.
In summary, the operational reality of the Safety Hub was rather less structured and more ‘organic’ than some participants had hoped, but it still delivered meaningful outcomes. The Safety Hub made its own valuable contribution to community safety while the difficulties it faced helped identify the need for a wider, linked-up ecosystem of community safety in Auckland city. The Hub has proved itself to be a viable concept, that diverse partners can work together in a shared space, and that the presence of volunteers does offer reassurance and can make people feel safer. However, those involved in the Hub also identified a range of challenges that need to be overcome if the Hub is to be more than just a base for increasing the visibility and presence of capable guardians.

text: Safety hubs and partnership policing: Coordination, collaboration and partnership working in Auckland city centre This report presents key insights from an exploratory study of the Safety Hub initiative that first appeared in the run up to the 2023 Women’s World Cup in Auckland. It highlights the potential and the pitfalls of partnership-based approaches to community safety in Aotearoa New Zealand. The study was based on a series of in-person focus group discussions and semi-structured interviews with key partners and stakeholders including Community Patrols New Zealand (CPNZ) volunteers, NZ Police (Auckland city Beat officers and Liaison staff), Auckland council staff and Ngā Watene Māori (Māori Wardens). Data collection for this study took place over a four-month period from November 2024 through to February 2025, structured around the availability of participants. The study employed a thematic analysis methodology to systematically identify and organise key themes and issues within the qualitative data gathered from interviews and focus groups.
In summary, the operational reality of the Safety Hub was rather less structured and more ‘organic’ than some participants had hoped, but it still delivered meaningful outcomes. The Safety Hub made its own valuable contribution to community safety while the difficulties it faced helped identify the need for a wider, linked-up ecosystem of community safety in Auckland city. The Hub has proved itself to be a viable concept, that diverse partners can work together in a shared space, and that the presence of volunteers does offer reassurance and can make people feel safer. However, those involved in the Hub also identified a range of challenges that need to be overcome if the Hub is to be more than just a base for increasing the visibility and presence of capable guardians.

year: 2025