Estimating returns to education: three natural experiment techniques compared

Andrew Leigh and Chris Ryan compare three quasi-experimental approaches to estimating the returns to schooling in Australia: instrumenting schooling using month of birth, instrumenting schooling using changes in compulsory schooling laws, and comparing outcomes for twins. Abstract With annual pre-tax income as our measure of income, we find that the naïve (OLS) returns to an additional year of schooling is 13%. The month of birth IV approach gives an 8% rate of return to schooling, while using changes in compulsory schooling laws as an IV produces a 12% rate of return. Finally, we review estimates from twins studies. While we estimate a higher return to education than previous studies, we believe that this is primarily due to the better measurement of income and schooling in our dataset. Australian twins studies are consistent with our findings insofar as they find little evidence of ability bias in the OLS rate of return to schooling. Our estimates of the ability bias in OLS estimates of the rate of return to schooling range from 9% to 39%. Overall, our findings suggest the Australian rate of return to education, corrected for ability bias, is around 10%, which is similar to the rate in Britain, Canada, the Netherlands, Norway and the United States

Estimating Returns to Education: Three Natural Experiment Techniques Compared

We compare three quasi-experimental approaches to estimating the returns to schooling in Australia: instrumenting schooling using month of birth, instrumenting schooling using changes in compulsory schooling laws, and comparing outcomes for twins. With annual pre-tax income as our measure of income, we find that the naïve (OLS) returns to an additional year of schooling is 13%. The month of birth IV approach gives an 8% rate of return to schooling, while using changes in compulsory schooling laws as an IV produces a 12% rate of return. Finally, we review estimates from twins studies. While we estimate a higher return to education than previous studies, we believe that this is primarily due to the better measurement of income and schooling in our dataset. Australian twins studies are consistent with our findings insofar as they find little evidence of ability bias in the OLS rate of return to schooling. Our estimates of the ability bias in OLS estimates of the rate of return to schooling range from 9% to 39%. Overall, our findings suggest the Australian rate of return to education, corrected for ability bias, is around 10%, which is similar to the rate in Britain, Canada, the Netherlands, Norway and the United States.returns to education, instrumental variables, compulsory schooling, twins, Australia

How and Why has Teacher Quality Changed in Australia?

International research suggests that differences in teacher performance can explain a large portion of student achievement. Yet little is known about how the quality of the Australian teaching profession has changed over time. Using consistent data on the academic aptitude of new teachers, we compare those who have entered the teaching profession in Australia over the past two decades. We find that the aptitude of new teachers has fallen considerably. Between 1983 and 2003, the average percentile rank of those entering teacher education fell from 74 to 61, while the average rank of new teachers fell from 70 to 62. One factor that seems to have changed substantially over this period is average teacher pay. Compared to non-teachers with a degree, average teacher pay fell substantially over the period 1983-2003. Another factor is pay dispersion in alternative occupations. During the 1980s and 1990s, non-teacher earnings at the top of the distribution rose faster than earnings at the middle and bottom of the distribution. For an individual with the potential to earn a wage at the 90th percentile of the distribution, a non-teaching occupation looked much more attractive in the 2000s than it did in the 1980s. We believe that both the fall in average teacher pay, and the rise in pay differentials in non-teaching occupations are responsible for the decline in the academic aptitude of new teachers over the past two decades.test scores, teacher salary, occupational choice

Long-Run Trends in School Productivity: Evidence From Australia

Outside the United States (U.S.), very little is known about long-run trends in school productivity. We present new evidence using two data series from Australia, where comparable tests are available back to the 1960s. For young teenagers (aged 13-14), we find a small but statistically significant fall in numeracy over the period 1964- 2003, and in both literacy and numeracy over the period 1975-1998. The decline is in the order of one-tenth to one-fifth of a standard deviation. Adjusting this decline for changes in student demographics does not affect this conclusion; if anything, the decline appears to be more acute. The available evidence also suggests that any changes in student attitudes, school violence, and television viewing are unlikely to have had a major impact on test scores. Real per-child school expenditure increased substantially over this period, implying a fall in school productivity. Although we cannot account for all the phenomena that might have affected school productivity, we identify a number of plausible explanations.education production function, literacy, numeracy

Duramycin-induced calcium release in cancer cells

Introduction: Duramycin through binding with phosphatidylethanolamine (PE) has shown potential to be an effective anti-tumour agent. However its mode of action in relation to tumour cells is not fully understood. Methods: PE expression on the surface of a panel of cancer cell lines was analysed using duramycin and subsequent antibody labelling then analysed by flow cytometry. Cell viability was also assessed via flow cytometry using annexin V and propidium iodide (PI). Calcium ion (Ca²⁺) release by tumour cells in response to duramycin was determined by spectrofluorometry following incubation with Fluo-3, AM. Confocal microscopy was performed on the cancer cell line AsPC-1 to assess real time cell response to duramycin treatment. Results: Duramycin was able to detect cell surface PE expression on all 15 cancer cell lines screened, which was shown to be duramycin concentration dependent. However higher concentrations induced necrotic cell death. Duramycin induced calcium ion (Ca²⁺) release from the cancer cell lines also in a concentration and time dependent manner. Confocal microscopy showed an influx of PI into the cells over time and induced morphological changes. Conclusion: Duramycin induces Ca²⁺ release from cancer cell lines in a time and concentration dependent relationship

Determining the sample size for a cluster-randomised trial: Bayesian hierarchical modelling of the ICC estimate

In common with many cluster-randomised trials, it was difficult to determine the appropriate sample size for the planned trial of the effectiveness of a systematic voiding programme for post-stroke incontinence due to the lack of a robust estimate of the intra-cluster correlation coefficient (ICC). One approach to overcome this problem is a method of combining ICC values in the Bayesian framework (Turner et al. 2005). We adopted this approach and used Bayesian hierarchical modelling to estimate the ICC

Audio Universe: Tour of the Solar System

We have created a show about the Solar System, freely available for both planetariums and home viewing, where objects in space are represented with sound as well as with visuals. For example, the audience listens to the stars appear above the European Southern Observatory's Very Large Telescope and they hear the planets orbit around their heads. The aim of this show is that it can be enjoyed and understood, irrespective of level of vision. Here we describe how we used our new computer code, STRAUSS, to convert data into sound for the show. We also discuss the lessons learnt during the design of the show, including how it was imperative to obtain a range of diverse perspectives from scientists, a composer and representatives of the blind and vision impaired community.Comment: Published in Astronomy and Geophysics, Volume 63, Issue 2, Pages 2.38-2.40. This is the authors' accepted version of the manuscript. Visit https://www.audiouniverse.org for audio-visual resources. Our new sonification code, STRAUSS, is available at: https://github.com/james-trayford/strauss. Article is 5 pages with 3 figure

AN INVESTIGATION INTO SEASONAL POWER CHANGES IN COLLEGIATE BASEBALL PITCHERS

This study aimed to investigate changes in power and fatigue of collegiate baseball pitchers throughout a season to determine injury risk. Isokinetic, mobility, and performance test records were reviewed for 18 male NCAA-I baseball athletes. Testing was performed during the offseason, season start, and end of non-conference play and included medicine ball throws, hop testing, and 3-speed isokinetic testing. Statistical analysis determined that the kneeling medicine ball throw, 6-m hop, and several isokinetic outcomes decreased throughout the season. Using a combination of medicine ball throws, hop testing, and isokinetic testing at specific times during a season may provide insight into the overall fatigue level and injury risk within baseball pitchers

Immersing the artist and designer in the needs of the clinician: evolving the brief for distraction and stress reduction in a new Child Protection Unit.

Engaging clinicians in the design of new, less stressful spaces in healthcare is an interdisciplinary challenge for artists and designers. The design brief is the primary means of ensuring shared understanding and success criteria for creative projects (Press and Cooper 2003) and highlights ambitions and constraints for the project. Conventionally the brief is prepared by the client and issued to the artist or designer. This assumes that the client knows at the outset how to articulate needs and is able to envisage the outcome. Alternative processes emerging through co-design and interdisciplinary working assume the brief is developed or evolved jointly as part of the process and is focused on the experience of the user. This paper focuses on the evolution of a meaningful brief for a Child Protection Unit in NHS Greater Glasgow & Clyde’s new Royal Hospital for Children. Development of the brief was driven by the art and design team and aimed at opening up mutual understanding with the clinicians. The visual mapping of dialogue between artist, interactive designer and clinicians provides a novel approach to understanding this key stage of the process. Fremantle co-ordinated the paper. Hepburn undertook the fieldwork and provided the analysis. Fremantle structured the paper and co-ordinated reviews with Hamilton and Sands

A physical investigation of wear and thermal characteristics of 3D printed nylon spur gears

For particular applications such as automotive and aerospace engineering, polymer gears have unique advantages over metal gears, such as: low cost and weight; high efficiency; quietness of operation; functioning without external lubrication; etc. The characteristics of wear and thermal behaviour of injection moulded gears have previously been studied [1], however, additive manufacturing (AM) and 3D printing processes have become increasingly popular for production of polymer components. It is generally understood that 3D printing is cost effective if production volumes are below 1000 units in comparison with plastic injection moulding [2]. The technology has been applied in wide range of industries, including the automotive, aerospace, medical and architectural industries [3]. The nature of 3D printing means that the process is inherently linked to the materials used and each 3D printing technology has a subset of materials that it is compatible with. For Fused Deposition Modelling (FDM) for instance there are many different materials available on the market including polylactic acid (PLA), acrylonitrile butadiene styrene (ABS), polycarbonate (PC), nylon and many others [4]. Due to the increased interest in 3D printing there is an increasing amount of research regarding the direct mechanical properties and thermal properties of 3D printed materials and their modification. Leigh et al. [5] introduced a low-cost conductive composite material for 3D printing of electronic sensosr. Christ et al. [6] increased the elastic strain of polyurethane through addition of multi wall carbon nanotubes. Blok et al. [7] claimed that adding continuous fibers could further increasing the tensile strength compared with carbon fibre nylon composites. Kalin et al. [8] Claimed that gear performance and durability could be affected by thermal properties with the result showing an increase in operating temperature could decreasing the life cycle of the gear. Hu and Mao [9] investigated misalignment effects on acetal gears together with wear behaviour, with the results demonstrating that acetal gears were most sensitive to pitch misalignment