title: Flood risk and property value: A case study analysing the effect of disclosed flood risk maps on the housing market in Hamilton, New Zealand

authors: Li, Chao

abstract: Flooding is among the most financially devastating natural disasters globally and in New Zealand. To manage flood risk, educating the public about its potential dangers is widely recognised as a necessity worldwide. However, in New Zealand, building development and property sales continue to thrive in officially designated flood risk areas, suggesting that published flood risk information may not be achieving its intended impact. This raises alarming concerns about whether the public effectively receives published flood risk information and to what extent it influences their decision making. However, empirical research on this topic is scarce in New Zealand, and the few existing studies only cover small portions of a case study area, lacking broader geographical representation and transferrable insights into long-term behavioural responses to flood risk information. This leaves local governments without reliable evidence to assess the effectiveness of flood risk disclosures and informed land-use decisions. One of the key reasons is the lack of nationally consistent flood risk mapping and the fragmented flood risk management approach across localities and regions, making flood risk information scattered, inconsistent, and difficult to access.
This research aims to address this gap by conducting a comprehensive empirical analysis in Hamilton City, New Zealand. Specifically, I focus on the holistic timeline of flood risk information released within the city since the first flood map was officially adopted in 2012. Specifically, Hamilton City Council (HCC) released flood risk maps and adopted them in the 2012 District Plan, followed by the introduction of online Floodviewer maps in 2020. Publishing flood risk information through two different platforms covering various urban spaces makes this a unique case study for examining the effects of flood risk on property prices. This research combines rigorous causal inference methods, including Difference-in-Differences (DID), Repeat-Sales models, and Hedonic modelling, to examine whether the release of flood risk information influences property sales in officially designated flood zones. The Results show that flood risk information has a limited impact on property prices in Hamilton City’s flood risk areas. However, in repeat sales analysis, disclosing flood risk information positively impacts housing value in these areas. These findings align with most historical research in New Zealand, indicating that it is not rare for people to disregard flood risk information in this country. This may be attributed to the absence of a unified national standard for published flood risk information and the lack of effective communication mechanisms.

text: Flood risk and property value: A case study analysing the effect of disclosed flood risk maps on the housing market in Hamilton, New Zealand Flooding is among the most financially devastating natural disasters globally and in New Zealand. To manage flood risk, educating the public about its potential dangers is widely recognised as a necessity worldwide. However, in New Zealand, building development and property sales continue to thrive in officially designated flood risk areas, suggesting that published flood risk information may not be achieving its intended impact. This raises alarming concerns about whether the public effectively receives published flood risk information and to what extent it influences their decision making. However, empirical research on this topic is scarce in New Zealand, and the few existing studies only cover small portions of a case study area, lacking broader geographical representation and transferrable insights into long-term behavioural responses to flood risk information. This leaves local governments without reliable evidence to assess the effectiveness of flood risk disclosures and informed land-use decisions. One of the key reasons is the lack of nationally consistent flood risk mapping and the fragmented flood risk management approach across localities and regions, making flood risk information scattered, inconsistent, and difficult to access.
This research aims to address this gap by conducting a comprehensive empirical analysis in Hamilton City, New Zealand. Specifically, I focus on the holistic timeline of flood risk information released within the city since the first flood map was officially adopted in 2012. Specifically, Hamilton City Council (HCC) released flood risk maps and adopted them in the 2012 District Plan, followed by the introduction of online Floodviewer maps in 2020. Publishing flood risk information through two different platforms covering various urban spaces makes this a unique case study for examining the effects of flood risk on property prices. This research combines rigorous causal inference methods, including Difference-in-Differences (DID), Repeat-Sales models, and Hedonic modelling, to examine whether the release of flood risk information influences property sales in officially designated flood zones. The Results show that flood risk information has a limited impact on property prices in Hamilton City’s flood risk areas. However, in repeat sales analysis, disclosing flood risk information positively impacts housing value in these areas. These findings align with most historical research in New Zealand, indicating that it is not rare for people to disregard flood risk information in this country. This may be attributed to the absence of a unified national standard for published flood risk information and the lack of effective communication mechanisms.

year: 2025

title: Experiences with a weighted decision tree learner

authors: Cleary, John G.

subjects: computer science

abstract: Machine learning algorithms for inferring decision trees typically choose a single “best” tree to describe the training data. Recent research has shown that classification performance can be significantly improved by voting predictions of multiple, independently produced decision trees. This paper describes an algorithm, OB1, that makes a weighted sum over many possible models. We describe one instance of OB1, that includes all possible decision trees as well as naïve Bayesian models. OB1 is compared with a number of other decision tree and instance based learning algorithms on some of the data sets from the UCI repository. Both an information gain and an accuracy measure are used for the comparison. On the information gain measure OB1 performs significantly better than all the other algorithms. On the accuracy measure it is significantly better than all the algorithms except naïve Bayes which performs comparably to OB1.

text: Experiences with a weighted decision tree learner Machine learning algorithms for inferring decision trees typically choose a single “best” tree to describe the training data. Recent research has shown that classification performance can be significantly improved by voting predictions of multiple, independently produced decision trees. This paper describes an algorithm, OB1, that makes a weighted sum over many possible models. We describe one instance of OB1, that includes all possible decision trees as well as naïve Bayesian models. OB1 is compared with a number of other decision tree and instance based learning algorithms on some of the data sets from the UCI repository. Both an information gain and an accuracy measure are used for the comparison. On the information gain measure OB1 performs significantly better than all the other algorithms. On the accuracy measure it is significantly better than all the algorithms except naïve Bayes which performs comparably to OB1.

year: 1998-05

title: Visitors' satisfaction with heritage sites in New Zealand: Causes and complexities, clusters and causes

authors: Trinh, Thi Thu

subjects: Heritage Tourism

abstract: The thesis presents findings from a survey of over 1,000 visitors at three New Zealand heritage sites. These sites were Te Puia, the Rotorua Bathhouse Museum and the Rangiriri Battlefield Interpretation Centre. All three represent a key period in New Zealand’s history from the period of approximately 1840 to 1900, but in the case of Te Puia there is also a continuing contemporary cultural importance. This last site, located in Rotorua, was founded as the Maori Arts and Crafts Institute and was established to perpetuate Maori tradition skills in areas such as carving and weaving. Its location was in part determined by the volcanic nature of the valley, long inhabited by members of Te Arawa tribal people. The site has a strong connection with tourism as Te Arawa have entertained tourists from the mid-nineteenth century in the volcanic area. The site therefore represents a tourism site from the perspective of history, culture and natural heritage. The Bathhouse Museum represents a period of late colonial architecture while the third site, the Rangiriri Battlefield is based on the remnants of the Pa (Maori fortifications) that was the site of a battle between the colonial government forces and the Maori Kingi movement on November 23rd 1840.

The motive for the research was to provide a profile of visitors for the respective sites and their management, and then to assess to what degree socio-demographics might be explanatory variables in determining future visitation. The core theories being employed revolved around concepts of levels of interest in heritage and historic sites, the intellectual search for knowledge, and the degree to which people became involved in the activity of heritage site visitation. The work was driven by the finding that only about 11 per cent of visits to cultural tourism sites were ‘purposeful’ tourists as defined by McKercher and Du Cros (2002). Being purposeful implies having specific degrees of interest, of becoming involved and possibly seeking meanings that implied senses of identity. That is, self-awareness accrued from having a better understanding of the past as a means of knowing about the present. This conceptualisation implies use of the theories of involvement, benefits and self-awareness, and the managerial aspects of interpretation.  Normally such an approach has been seen by many researchers as a determinant of satisfaction, but in this thesis satisfaction is not seen as simply an end to a process. Rather, this thesis argues that to be satisfied entails not only cognitive and affective components, but also the conative. That conative component can include making recommendations to others, making visits to other heritage sites, or joining organisations associated with heritage sites such as the New Zealand Historic Place Trust. These form key themes in the literature review.

Unfortunately, while these premises emerged from the literature review and informed the hypotheses that are later described in the thesis, they were not wholly supported by the data. It is suggested that one reason for this, from a statistical perspective, was that measures used were subject to multi-collinearity and auto-correlation – put simply, many of the variables are not independent from each other. For example, it is suggested that satisfaction is actually enhanced by subsequently being able to make recommendations to friends and others; that the act of making a recommendation enhances one’s own self in both the eyes of that friend or through an enhanced self- perception of being helpful, and thus auto-correlation may exist between these variables.

This realisation thus leads, in the conclusions of Chapter Eight, to new suggestions for potential future researchers concerning ways of looking at the nature of involvement that draw on distinctions between situational and enduring involvement. Finally, it also needs to be noted that tourists are not lay historians, but are the makers of their holidays, and hence the debate is contextualised within the act of being on holiday, which itself is a period of escape and relaxation for many. Hence the relationships being examined in this thesis are complex, interactive and yet rewarding to untangle.

text: Visitors' satisfaction with heritage sites in New Zealand: Causes and complexities, clusters and causes The thesis presents findings from a survey of over 1,000 visitors at three New Zealand heritage sites. These sites were Te Puia, the Rotorua Bathhouse Museum and the Rangiriri Battlefield Interpretation Centre. All three represent a key period in New Zealand’s history from the period of approximately 1840 to 1900, but in the case of Te Puia there is also a continuing contemporary cultural importance. This last site, located in Rotorua, was founded as the Maori Arts and Crafts Institute and was established to perpetuate Maori tradition skills in areas such as carving and weaving. Its location was in part determined by the volcanic nature of the valley, long inhabited by members of Te Arawa tribal people. The site has a strong connection with tourism as Te Arawa have entertained tourists from the mid-nineteenth century in the volcanic area. The site therefore represents a tourism site from the perspective of history, culture and natural heritage. The Bathhouse Museum represents a period of late colonial architecture while the third site, the Rangiriri Battlefield is based on the remnants of the Pa (Maori fortifications) that was the site of a battle between the colonial government forces and the Maori Kingi movement on November 23rd 1840.

The motive for the research was to provide a profile of visitors for the respective sites and their management, and then to assess to what degree socio-demographics might be explanatory variables in determining future visitation. The core theories being employed revolved around concepts of levels of interest in heritage and historic sites, the intellectual search for knowledge, and the degree to which people became involved in the activity of heritage site visitation. The work was driven by the finding that only about 11 per cent of visits to cultural tourism sites were ‘purposeful’ tourists as defined by McKercher and Du Cros (2002). Being purposeful implies having specific degrees of interest, of becoming involved and possibly seeking meanings that implied senses of identity. That is, self-awareness accrued from having a better understanding of the past as a means of knowing about the present. This conceptualisation implies use of the theories of involvement, benefits and self-awareness, and the managerial aspects of interpretation.  Normally such an approach has been seen by many researchers as a determinant of satisfaction, but in this thesis satisfaction is not seen as simply an end to a process. Rather, this thesis argues that to be satisfied entails not only cognitive and affective components, but also the conative. That conative component can include making recommendations to others, making visits to other heritage sites, or joining organisations associated with heritage sites such as the New Zealand Historic Place Trust. These form key themes in the literature review.

Unfortunately, while these premises emerged from the literature review and informed the hypotheses that are later described in the thesis, they were not wholly supported by the data. It is suggested that one reason for this, from a statistical perspective, was that measures used were subject to multi-collinearity and auto-correlation – put simply, many of the variables are not independent from each other. For example, it is suggested that satisfaction is actually enhanced by subsequently being able to make recommendations to friends and others; that the act of making a recommendation enhances one’s own self in both the eyes of that friend or through an enhanced self- perception of being helpful, and thus auto-correlation may exist between these variables.

This realisation thus leads, in the conclusions of Chapter Eight, to new suggestions for potential future researchers concerning ways of looking at the nature of involvement that draw on distinctions between situational and enduring involvement. Finally, it also needs to be noted that tourists are not lay historians, but are the makers of their holidays, and hence the debate is contextualised within the act of being on holiday, which itself is a period of escape and relaxation for many. Hence the relationships being examined in this thesis are complex, interactive and yet rewarding to untangle.

year: 2013