An Analysis of Job Mobility and Earnings in New Zealand

The movement of workers between jobs may play an important role in determining both the average level and overall dispersion in earnings in an economy. Yet, there has been almost no research to date on the extent and nature of job mobility and its possible consequences for individual earnings in New Zealand. This study provides some initial empirical results on this topic using administrative data provided by Statistics New Zealand (Linked Employee-Employer Data). We find that job mobility is extensive, but that high rates of job separation during the first year or two in a job eventually dissipate with tenure. Job mobility is generally higher among teenagers and young adults, but differences by gender are minimal. In fact, overall job mobility is generally higher for men than women. Individuals changing jobs receive monthly earnings that are, on average, below the earnings received by individuals who do not change jobs/ We find that job changes are associated with a narrowing in this earnings gap. However, this result disappears once we control for a wide variety of other determinants of earnings growth, Firm characteristics appear to play important roles in the relationship between job mobility and earnings. A move to a larger firm (i.e one with more employees) and a firm that pays higher average earnings to all its employees can result in a substantial increase in individual earnings. Earnings growth is also found to be negatively related to the time interval between jobs, and the initial earnings of the individual. Once we hold these individual and firm characteristics constant, however, job changes by themselves lead to a relative decline in earnings growth

Final Regression Results on the Cognitive Achievement of Children in the Christchurch Health and Development Study with Corrections for Attrition from this Longitudinal Study

Econometric analyses of the cognitive development of children have been hampered by data limitations and a variety of methodological and specification issues. Structural models allow for complex causal relationships between child achievement and inputs from parents, schools and communities, but these effects are difficult to isolate. Even reduced-form models suffer from both omitted-variable (e.g., unobserved family and community investments) and simultaneous-equation bias (e.g., endogenous private schooling and class size). The use of panel data offers the best non-experimental solution to these estimation issues. With multiple observations on test performance of children between the ages of 8 and 13 in the Christchurch Health and Development Study, we are able to hold constant individual- specific, time-invariant factors that influence cognitive achievement. These data permit several insights into the dynamic nature of this cognitive achievement process. We cannot reject the null hypothesis that the lagged dependent variable serves as a “sufficient statistic” for all past determinants of cognitive achievement. This provides the first statistical justification for the “value-added approach” recommended of Hanushek (1986), and actually diminishes the need for these longer longitudinal studies. Procedures are developed for testing for the presence of unobserved fixed-effects in this cognitive development process, and correcting for the effects of attrition from this panel. No evidence is found that the value-added to cognitive achievement is influenced by the number of parents in the family, the work status of the mother, the benefit status of the family, the income of the family and the type of school attended. Evidence is also found of a positive effect of class size on cognitive development. Our interpretation is that class size is endogenous, and the causality may be reversed (i.e., children with poor reading performances are intentionally placed in smaller classes). Yet, no evidence is found of the hypothesised negative effect of class size on cognitive achievement with an anti- instrumental-variable approach.

Ethnicity and Early Labour Market Experiences in the Christchurch Health and Development Study

This study uses data from the Christchurch Health and Development Study to investigate differences by ethnicity in early labour market experiences of a birth cohort born in Christchurch in 1977. The study finds that Maori youth acquire fewer school and post-school qualifications, and accumulate less work experience by age 21, than other youth. There is also more heterogeneity among Maori than other youth – a substantially larger proportion of Maori youth, compared to others, accumulate very little time in these productive activities. Even though measured background factors are important in explaining the relatively lower accumulation of work experience by Maori, they do not explain the entire ethnic gap in labour market outcome. However, in multivariate analyses, Maori ethnicity has an insignificant, though negative effect on work experience. At age 21, Maori workers in this study (which is not nationally representative) on average receive higher hourly earnings than non-Maori workers, though this difference is not statistically significant. Once differences in other characteristics are taken into account, particularly educational qualifications and work experience, which have a positive effect on earnings, the earnings difference between Maori and non-Maori is statistically significant. This may be due to other unobserved differences between Maori and non-Maori who are employed, that also have an effect on earnings.Christchurch Health and Development Study, ethnicity, labour market outcomes

Kimberley points of Western Australia: Pressure flaking, projections and prestige

Kimberley points are pressure flaked bifaces with marginal projections, produced within the last millennium, in north Western Australia. These points were hafted for hunting and fighting in recent times, although there is some suggestion that smaller points tended to be hafted for use in favour of larger points, which were reserved for trade and exchange. Kimberley Points are imbued with strong social signalling and prestige qualities, known from Historic times. This paper examines whether these qualities are reflected archaeologically in their marginal projections produced with pressure flaking; and their morphology and production. Multiple sources of Kimberley Point archaeology, ethnography, and production are critically reviewed. As prestige items, the marginal projections are found to very likely relate to their social value, rather than functional drive, which this study investigates using morphological approaches. Samples from both ethnographic collections and archaeological surface assemblages are analysed. The study finds that biface elongation, length and perimeter length each greatly influenced the number of and size of marginal projections, regardless of raw material. This aspect of production probably reflects the value and social prestige for large serrated points, likely produced by the knapper before an audience in virtuoso displays of pressure flaking. It is conceivable that these complex social practices emerged around 1,000 years ago. This study provides a rare glimpse into the social values of stone tool produces, and links archaeological data to social values in the past

Effects of Drilling Small Diameter Exhaust Shafts in a Gassy Longwall Operation

As the title indicates, this paper deals with the ventilation of a gassy longwall mine through the use of small diameter exhaust shafts. Extensive background information is provided to show the evolution of the mine\u27s ventilation system to correspond with changes in longwall mining techniques, particularly increases in face width. A description of the blind drilled shaft techniques, which proved to be the most economical ventilation choice for US Steel No. 50 Mine, is also included

An Analysis of Job Mobility and Earnings in New Zealand

The movement of workers between jobs may play an important role in determining both the average level and overall dispersion in earnings in an economy. Yet, there has been almost no research to date on the extent and nature of job mobility and its possible consequences for individual earnings in New Zealand. This study provides some initial empirical results on this topic using administrative data provided by Statistics New Zealand (Linked Employee-Employer Data). We find that job mobility is extensive, but that high rates of job separation during the first year or two in a job eventually dissipate with tenure. Job mobility is generally higher among teenagers and young adults, but differences by gender are minimal. In fact, overall job mobility is generally higher for men than women. Individuals changing jobs receive monthly earnings that are, on average, below the earnings received by individuals who do not change jobs/ We find that job changes are associated with a narrowing in this earnings gap. However, this result disappears once we control for a wide variety of other determinants of earnings growth, Firm characteristics appear to play important roles in the relationship between job mobility and earnings. A move to a larger firm (i.e one with more employees) and a firm that pays higher average earnings to all its employees can result in a substantial increase in individual earnings. Earnings growth is also found to be negatively related to the time interval between jobs, and the initial earnings of the individual. Once we hold these individual and firm characteristics constant, however, job changes by themselves lead to a relative decline in earnings growth

Cave stratigraphies and cave breccias: Implications for sediment accumulation and removal models and interpreting the record of human occupation

AbstractMany of the key debates in archaeology hinge on the chronology and interpretation of data gathered from cave and rockshelter stratigraphies, especially those in karstic limestone environments which are selectively targeted by archaeologists because of their superior preservation characteristics. It has long been recognized that such sites often contain a variety of cemented deposits including cave breccias and that some breccias contain anthropogenic inclusions such as stone artefacts, shell and burnt animal bones. Cementation enhances the survival through time of such brecciated deposits. This can result in chrono-stratigraphic intervals surviving on cave walls and speleothems that are no longer represented in the stratigraphy of cave floors. This has important implications for understanding apparent presence/absence of human occupation and cultural continuity as seen in archaeo-stratigraphy in caves and rockshelters, especially in relation to human migration in the humid tropics in SE Asia and the Pacific, and over Pleistocene to Holocene timescales. Here we discuss localized breccia formation, the erosional processes that leave remnant deposits adhering to walls and speleothems at heights well above current cave floors, and the possible significance of local and regional processes, especially changing base levels, in triggering gutting out phases impacting cave floor sediment architectures. Equally significant in terms of chronological completeness, representativeness and bias is the contribution made by cultural materials encased in older breccias as they erode and are (re-)incorporated into younger accumulating cultural deposits. Case studies from cave sites in Papua New Guinea and Timor Leste are used to illustrate these issues

Late Pleistocene/early Holocene maritime interaction in Southeastern Indonesia - Timor Leste

This study analysed over 1000 obsidian stone artefacts excavated from two adjoining shelters at Tron Bon Lei on Alor Island Indonesia using portable XRF. The study showed an unambiguous separation of three different source locations (Groups 1, 2 and 3). Two sources (Group 2 and 3a, b, c) dominate the assemblage numerically. Group 1 and 2 indicate use of a single volcanic formation with a strong match between Group 1 artefacts and artefacts from sites in Timor Leste. Obsidian occurs in the earliest occupation layer in the Alor sites but does not include Group 1 artefacts which occur only after approx. 12,000 cal BP. Currently the geographical location of the Group 1 outcrop is unknown, however, based on the late appearance of the Group 1 artefacts in the Alor sequence it is likely that the location is not on Alor, but rather on another island of the Sunda chain. The dating of Group 1 artefacts in widely spaced sites on the never geographically connected islands of Timor and Alor indicates that maritime interaction between islands began by at least the terminal Pleistocene. The distribution of the obsidian in Tron Bon Lei shelter Pit B shows that there were periods of more intense interaction punctuated by periods when interaction declined or ceased

Technological organisation and points in the southern Kimberley

The anthropogenic manipulation of stone is ubiquitous in every part of the world, throughout human prehistory. The durability of stone technologies creates an enduring material link between the tool maker and the archaeologist, particularly in Australia, where stone tools are a dominant component of the extant archaeological record, and as such, provide fundamental access to our understanding of the technology and lifeways of Australia’s Indigenous ancestors. This research, which is part of the ARC Linkage project: Lifeways of the First Australians, analyses stone artefacts from excavated and surface assemblages in the southern Kimberley region. This thesis by compilation focuses on the technological development of points, which are a distinctive, Holocene component of the Australian lithic suite, in order to test a series of hypotheses, which are presented in a collection of published manuscripts, and unpublished manuscripts currently being reviewed. Lithic artefacts are produced by reduction. When a stone is worked into a tool, it reduces in size, with some fragments resulting in usable pieces, others in debitage. The process of reduction forms the basic premise for this thesis, where reduction is quantified by a morphological methodology outlined in Chapters 1 and 2, and applied to a number of assemblages in order to reconstruct the life history of stone tools from the Kimberley region (Chapters 3 – 7). Chapter 3 presents a robust chronology for point technology in the Kimberley region, where direct percussion points first appear in the archaeological record between 6,000 and 5,000 years ago, and Kimberley Points appear within the last 1,000 years. Chapter 4 provides detailed examination of a large, excavated point assemblage from the Mt Behn rock shelter. This analysis demonstrates that points were produced within a reduction continuum, where changes in reduction intensity and artefact morphology were sensitive to environmental change during the mid to late Holocene. Chapter 5 presents analyses of multiple surface assemblages across the Kimberley, where backing technology is shown to be a regular component of point technologies. The presence of the Kimberley Backed Point challenges the existing model of spatial distributions of backing in Australia. Chapter 6 presents a remarkable point from Carpenters Gap 1, which was recovered with sizable portions of adhering hafting resin, an organic resin which was directly dated. This artefact provides the most compelling evidence for hafting technology used in the mid to late Holocene, and reveals that people were hafting small, lightly reduced points with both mastic and binding. Chapter 7 employs a novel approach to model the level of pedagogy, or teaching and learning, present in two different point reduction sequences. This manuscript demonstrates that pedagogy can be gleaned from stone artefact assemblages, and shows that Kimberley Points represent a shift towards a greater emphasis on a formal pedagogy within the last millennium of Kimberley prehistory. Finally, this thesis culminates in Chapter 8, which presents a summary of the conclusions and discussions offered throughout the manuscripts, and recommends areas of research for further investigation