title: Using panel data to exactly estimate under-reporting by the self-employed

authors: Kim, Bonggeun

subjects: Engle curve

abstract: The income of the self-employed is often assumed to be understated in economic statistics. Debate exists about the extent of under-reporting and the resulting measures of the size of the underground economy. This paper refines a method developed by Pissarides and Weber (1989) and uses discrepancies between food shares and reported incomes to estimate under-reporting by the self-employed. In contrast to previous studies our panel data methodology distinguishes income under-reporting from transitory income fluctuations of the self-employed, and provides an exact estimate of the degree of under-reporting rather than just an interval estimate. Using panel data from Korea and Russia we estimate that 38 percent of the income of self-employed households in Korea and 47 percent of the income of Russian self-employed households is not reported.

text: Using panel data to exactly estimate under-reporting by the self-employed The income of the self-employed is often assumed to be understated in economic statistics. Debate exists about the extent of under-reporting and the resulting measures of the size of the underground economy. This paper refines a method developed by Pissarides and Weber (1989) and uses discrepancies between food shares and reported incomes to estimate under-reporting by the self-employed. In contrast to previous studies our panel data methodology distinguishes income under-reporting from transitory income fluctuations of the self-employed, and provides an exact estimate of the degree of under-reporting rather than just an interval estimate. Using panel data from Korea and Russia we estimate that 38 percent of the income of self-employed households in Korea and 47 percent of the income of Russian self-employed households is not reported.

year: 2008-10

title: Exporting as a dynamic process: a study of New Zealand specialist food exporters

authors: Ronayne, Edmond Gregers

abstract: The object of this study was to understand the export process by conducting case study research among New Zealand specialist food exporters. Past export research has used quantitative approaches to determine the influence of firm and environmental variables on quantitative measures of superior export performance. This approach has suggested that export processes are static and unidirectional; conceptualisations which contrast with the dynamic change that is apparent in firm export activities seen through export experience or even casual observation. It was in an effort to understand this changing export process that this study was undertaken. 

Among the firm factors identified as influencing superior export performance are the perceptions of firm management. These perceptions change over time and those of export performance are specifically noted as influencing management perceptions. This study draws on these concepts of management perceptions and the role of strategy in the export process to ask “in which ways does export performance influence the export strategy process?” As a basis to frame and advance the study, the findings of past export research and its allusion to the role of performance perceptions were used to develop a research model.

The research question suggested an approach that would allow the researcher to get close to the research context; this was achieved using a methodology of phenomenology. To implement this research approach, case study, in a multiple case design, was used to gain insight into the perceptions of informants. The study was further facilitated by using the dynamic context provided by New Zealand specialist food exporters, from which eight case firms were selected using export and business criteria.

Interviews with management were the principal source of evidence. Evidence gathering was carried out concurrently with the analysis of evidence. This allowed earlier informant evidence to inform subsequent evidence gathering. Analysis used a variety of instruments to increase focus in case data, providing a basis for the development of the study’s findings. Consistency across cases in field work and analysis was underwritten by the use of a case study protocol and specialised computer software to maintain a case study data base.

Informant evidence indicated that export practitioners in case firms had a wider perception of export performance than past export research had suggested. These perceptions derive from streams of indicators of performance and contextual situations arising from export activities. The management perceptions that these indicators engender are applied in firm export strategy processes.

While the focus on export activity indicators varies according to firm organisational structure, the use of a range of indicators was a feature of all firms in the study.

These flows of indicator information and the perceptions and changes that they generated were part of a dynamic cycle of export activities. This process saw firm export strategy continuously reviewed, reformulated and implemented as it was adapted to address perceived changes in firm performance and context. These findings lead to the development of a conceptual model of a dynamic export process across case firms.

The dynamic export process identified in this study is a significant extension of past static cross-sectional conceptualisations of the export process. It suggests that export practitioners draw upon a wide range of export activity indicators to build perceptions of export outcomes and their export context. These perceptions inform and influence future export strategy and in turn, future export outcomes. This contribution to export research provides an understanding of the dynamic export process that is close to the reality of export practitioners. This understanding allows researchers, exporting firms and policy makers to conceptualise the export process in terms that are close to actual export practice. In addition, these exploratory findings of a dynamic export process provide a platform for further research to consider the application of this conceptualisation across exporting firms as a whole.

text: Exporting as a dynamic process: a study of New Zealand specialist food exporters The object of this study was to understand the export process by conducting case study research among New Zealand specialist food exporters. Past export research has used quantitative approaches to determine the influence of firm and environmental variables on quantitative measures of superior export performance. This approach has suggested that export processes are static and unidirectional; conceptualisations which contrast with the dynamic change that is apparent in firm export activities seen through export experience or even casual observation. It was in an effort to understand this changing export process that this study was undertaken. 

Among the firm factors identified as influencing superior export performance are the perceptions of firm management. These perceptions change over time and those of export performance are specifically noted as influencing management perceptions. This study draws on these concepts of management perceptions and the role of strategy in the export process to ask “in which ways does export performance influence the export strategy process?” As a basis to frame and advance the study, the findings of past export research and its allusion to the role of performance perceptions were used to develop a research model.

The research question suggested an approach that would allow the researcher to get close to the research context; this was achieved using a methodology of phenomenology. To implement this research approach, case study, in a multiple case design, was used to gain insight into the perceptions of informants. The study was further facilitated by using the dynamic context provided by New Zealand specialist food exporters, from which eight case firms were selected using export and business criteria.

Interviews with management were the principal source of evidence. Evidence gathering was carried out concurrently with the analysis of evidence. This allowed earlier informant evidence to inform subsequent evidence gathering. Analysis used a variety of instruments to increase focus in case data, providing a basis for the development of the study’s findings. Consistency across cases in field work and analysis was underwritten by the use of a case study protocol and specialised computer software to maintain a case study data base.

Informant evidence indicated that export practitioners in case firms had a wider perception of export performance than past export research had suggested. These perceptions derive from streams of indicators of performance and contextual situations arising from export activities. The management perceptions that these indicators engender are applied in firm export strategy processes.

While the focus on export activity indicators varies according to firm organisational structure, the use of a range of indicators was a feature of all firms in the study.

These flows of indicator information and the perceptions and changes that they generated were part of a dynamic cycle of export activities. This process saw firm export strategy continuously reviewed, reformulated and implemented as it was adapted to address perceived changes in firm performance and context. These findings lead to the development of a conceptual model of a dynamic export process across case firms.

The dynamic export process identified in this study is a significant extension of past static cross-sectional conceptualisations of the export process. It suggests that export practitioners draw upon a wide range of export activity indicators to build perceptions of export outcomes and their export context. These perceptions inform and influence future export strategy and in turn, future export outcomes. This contribution to export research provides an understanding of the dynamic export process that is close to the reality of export practitioners. This understanding allows researchers, exporting firms and policy makers to conceptualise the export process in terms that are close to actual export practice. In addition, these exploratory findings of a dynamic export process provide a platform for further research to consider the application of this conceptualisation across exporting firms as a whole.

year: 2003

title: Effects of lake trophic state and seasonal cycling on production and bioaccumulation of methylmercury in Te Arawa Lakes

authors: Chong, Grace-Lynn

abstract: There are natural sources of Mercury in New Zealand, primarily derived from volcanic activity and geothermal vents. Mercury (Hg) and its organic derivative, methylmercury (MeHg), are highly toxic to both the environment and human health. Of particular concern is the ability of MeHg to bioaccumulate in aquatic food webs, leading to increased toxicity in higher trophic organisms. Given that fish constitute a significant component of the local diet, comprehensive monitoring of Hg and MeHg concentrations is essential for developing effective mitigation strategies. Such efforts are critical to controlling Hg contamination in the environment and aquatic biota, as well as informing the public about lakes with elevated mercury levels. Previous Hg studies in New Zealand have been limited in scope, with monitoring efforts focused on only a few lakes rather than a comprehensive assessment across multiple ecosystems. Additionally, most existing research has primarily examined elemental Hg, with limited investigation into the distribution and bioavailability of MeHg.   

This study aims to comprehensively assess Hg and MeHg concentrations in 11 lakes of the Taupo Volcanic Zone. The study assessed Hg and MeHg concentrations in lake water and aquatic biota, including trout, crayfish (koura), and mussels (kakahi). To achieve this, Hg and MeHg in the water were measured using diffusive gradients in thin films (DGT) samplers, while tissue analyses determined Hg, MeHg and additional trace elements in the selected species. The findings of this study are expected to clarify the distribution and bioaccumulation of Hg and MeHg within lake ecosystems and to elucidate their transfer through the aquatic food web. These results will provide a scientific basis for assessing ecological and human health risks associated with mercury exposure, particularly for culturally and recreationally important species. The outcomes will inform lake management and monitoring strategies by identifying key pathways of mercury uptake and potential bioindicator species, and may guide the development of targeted mitigation measures, such as catchment management or advisories on species consumption. Collectively, this research will support evidence-based decision-making for freshwater ecosystem protection and long-term contaminant management.  

The results of this study revealed that total mercury (THg) and MeHg concentrations in trout, koura, and kakahi from Lakes Rotorua, Rotoiti, and Rotomahana exceeded WHO recommended safety thresholds. This study also found that a substantial proportion of THg was comprised of MeHg, which was predominantly accumulated in muscle tissue, whereas THg was primarily concentrated in the liver. The findings further indicated that eutrophication, lake stratification and hypolimnetic anoxia contribute to the enhanced production and bioaccumulation of Hg and MeHg within these aquatic systems. Additionally, selenium (Se) demonstrated a potential protective effect against MeHg toxicity in aquatic organisms.

text: Effects of lake trophic state and seasonal cycling on production and bioaccumulation of methylmercury in Te Arawa Lakes There are natural sources of Mercury in New Zealand, primarily derived from volcanic activity and geothermal vents. Mercury (Hg) and its organic derivative, methylmercury (MeHg), are highly toxic to both the environment and human health. Of particular concern is the ability of MeHg to bioaccumulate in aquatic food webs, leading to increased toxicity in higher trophic organisms. Given that fish constitute a significant component of the local diet, comprehensive monitoring of Hg and MeHg concentrations is essential for developing effective mitigation strategies. Such efforts are critical to controlling Hg contamination in the environment and aquatic biota, as well as informing the public about lakes with elevated mercury levels. Previous Hg studies in New Zealand have been limited in scope, with monitoring efforts focused on only a few lakes rather than a comprehensive assessment across multiple ecosystems. Additionally, most existing research has primarily examined elemental Hg, with limited investigation into the distribution and bioavailability of MeHg.   

This study aims to comprehensively assess Hg and MeHg concentrations in 11 lakes of the Taupo Volcanic Zone. The study assessed Hg and MeHg concentrations in lake water and aquatic biota, including trout, crayfish (koura), and mussels (kakahi). To achieve this, Hg and MeHg in the water were measured using diffusive gradients in thin films (DGT) samplers, while tissue analyses determined Hg, MeHg and additional trace elements in the selected species. The findings of this study are expected to clarify the distribution and bioaccumulation of Hg and MeHg within lake ecosystems and to elucidate their transfer through the aquatic food web. These results will provide a scientific basis for assessing ecological and human health risks associated with mercury exposure, particularly for culturally and recreationally important species. The outcomes will inform lake management and monitoring strategies by identifying key pathways of mercury uptake and potential bioindicator species, and may guide the development of targeted mitigation measures, such as catchment management or advisories on species consumption. Collectively, this research will support evidence-based decision-making for freshwater ecosystem protection and long-term contaminant management.  

The results of this study revealed that total mercury (THg) and MeHg concentrations in trout, koura, and kakahi from Lakes Rotorua, Rotoiti, and Rotomahana exceeded WHO recommended safety thresholds. This study also found that a substantial proportion of THg was comprised of MeHg, which was predominantly accumulated in muscle tissue, whereas THg was primarily concentrated in the liver. The findings further indicated that eutrophication, lake stratification and hypolimnetic anoxia contribute to the enhanced production and bioaccumulation of Hg and MeHg within these aquatic systems. Additionally, selenium (Se) demonstrated a potential protective effect against MeHg toxicity in aquatic organisms.

year: 2025