147 research outputs found
The analysis of pretender building price forecasting performance: a case study
No full textThe financial management of the construction procurement process is dependent upon on the performance of the managers involved. This paper describes an analysis of pre-tender building price forecasts (estimates) made by a Hong Kong consulting organisation for a series of 89 building projects from 1995 to 1997 to identify factors influencing the accuracy of the forecasts made for possible improvement in performance. This involved the consideration of two distinct sets of models the purpose of which was (1) to identify and explain the underlying systematic causes of errors and (2) to assist in improving the predictive ability of the forecasts.\ud
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The analysis for (1) first followed the conventional approach of summarising the distributional characteristics of the errors for subgroups of each of the variables available – building size (value), building size (floor area), forecasting (estimating) method (approximate quantities and superficial), nature of the work (new build and alteration work), type of client and type of project. The statistical results of this analysis (ANOVA) showed the only significant effect, in both bias and consistency, to be the forecasting method used. This was followed by the recently developed Gunner-Skitmore Price Intensity (PI) theoretic analysis, which simultaneously removed the confounding effects of the conventional treatment and confirmed the applicability of PI theory to the case study.\ud
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The analysis for (2) involved regressing all the independent variables, and a variety of transformations, on an additive as well as multiplicative version of the dependent variable, using cross-validation analysis to simulate the ex-post errors. No significant improvement on current practice was possible.\ud
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It is concluded that the forecasting performance of the case study company was excellent for the period under study, in terms of both relative accuracy and resistance to improvement by statistical modelling.\ud
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The original aspects of the paper are:\ud
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1 The provision of a new data set\ud
2 The first direct comparison of accuracy of conventional forecasting (estimating) methods since the 1950s and only the second ever.\ud
3 A new, simplified, approach is used, which involves partialling out the effects of price intensity before testing for the effects of other variables.\ud
4 The first confirmation of Gunner-Skitmore’s PI theory since the original paper\ud
5 The first conscious application of PI theory to prediction (as opposed to explanation)\ud
6 For the first time, current practice is shown to be near-optimal, in terms of resistance to improvement by statistical modelling\ud
7 The method described contributes to a variety of potential methods for benchmarking practice and quality monitoring/improvemen
The variance of elemental estimates
No full textOne of the factors affecting the success or otherwise of the procurement process is the quality of its financial management. In many cases, particularly in the early stages of a project, this is dependent on the accuracy of forecasts of future costs. For risk management purposes, what is most useful is the representation of future costs in the form of a probability distribution. In the case of early stage building contract price forecasts the approximate distribution of the likely error is usually obtained by the stochastic simulation of values from the distribution of known elemental rates under the simplifying assumption that the elemental rates are from independent random variables. This paper describes an empirical study aimed at investigating the accuracy of this method in comparison with one which incorporates the intervariable correlations. This confirms previous work in showing that the estimated second moment (variance) is considerably different when using the mean element rates as estimators, with the approximate method producing much lower estimates. It is then shown that, under the empirically supported assumption that element rates are normally distributed, the total project is also lognormally distributed and that this is completely specified. It is also shown that the coefficient of variation is unaffected by the size (floor area) of the project. The analysis then continues to examine the role of professional judgement and, with the simulated data used, the independent approximation is shown to be reasonably accurate – the professional judgement absorbing most of the intercorrelations involved. A final example is given involving the use of elemental unit quantities and rates. This shows how a unique project rate variance can be calculated for an individual future project, based on relevant data from previous projects and taking into account interelemental rate correlations. The results again suggests that the approximating method may be quite accurate
The accuracy of pre-tender building price forecasts: An analysis of USA data
No full textFor client expenditure management, risk analysis demands good estimates of the range of possible expenditures likely to occur and their probability of occurrence, while risk management is aided by reducing the range of possibilities. \ud
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This paper describes the analysis of a new and updated data set of the pre-tender estimating performance of a USA consulting organisation. It is shown that, with a coefficient of variation of 7.82%, the organisation is the leading non-contractor of those surveyed to date. The analysis then continues to seek a means of improving the estimating performance further by the empirical identification of factors influencing forecasting accuracy. The result of this is to show that, after partialling out the effects of confounding variables, year by year changes account for all the systematic errors that could be detected. These changes are then shown to be significantly correlated with the USA annual inflation rate and a regression model is used to examine the possible effects of adjusting for this in the estimation process
Bid Spread: an analysis of Hong Kong data
No full textAnalysis of the difference between the lowest and second lowest bids, or bid-spread, in a ‘lowest wins’ auction is of possible value in strategic bidding; providing an indication of mistakes in bids; determining a justifiable amount of bid security; and a means of providing some insight into the consequences of non-traditional auction arrangements. Bid-spread analysis, as developed in this paper, provides some explanations concerning the nature of bids and their statistical properties. In particular, it is shown here that, through the analysis of a data set of Hong Kong bidding data, that the bid-spread is directly (lineally) proportional to the contract size value. The percentage bid-spread is found to be a function of the number of bidders and the lower order statistics of the uniform density function
Factors influencing the development of Hong Kong’s construction industry : a qualitative study
No full textConstruction industry development has drawn attention for decades. However, there have been very few conceptual models which provide theoretical constructs to the knowledge base of construction industry development. The research on which this paper is based, aimed to validate a generic model developed by Fox (2003a) for the development of international construction by using Hong Kong’s construction industry as a case study. Semi-structured interviews with key stakeholders in Hong Kong’s construction industry were conducted. Stakeholders included construction clients, consultants, contractors, designers, educators/trainers, government officials, professional bodies, quasi-government officials, researchers, material and plant suppliers, construction lawyers, trades unions, and politicians. Results indicate that the factors influencing the industry are largely in line with Fox’s generic model and that cultural factors are particularly important. These findings are not only relevant to the development of the construction industry in Hong Kong but also to the industry worldwid
Habiter l'hexagone, centre collecteur d'Eysins (VD)
No full textEst-il possible de réutiliser ce patrimoine industriel que sont les silos à grains en Suisse ? Ce projet propose de reconvertir le centre collecteur d’Eysins en y intégrant de nouveaux programmes, tout en valorisant sa volumétrie si caractéristique, due à ses cellules de forme hexagonale. La réflexion s’est portée sur trois niveaux en parallèle: l’intervention à l’échelle du bâtiment, la spatialité d’un logement type et la construction d’une structure horizontale dans les cellules. Une fois le relevé du bâtiment existant effectué, l’approche choisie a été d’appréhender ce monument de béton en deux volumes distincts. D’un côté, la tour accueille des locaux administratifs modulables et de l’autre, les cellules hexagonales abritent des logements en duplex. La façade est le résultat d’une réflexion soigneuse qui propose une alternance entre de petites perforations dans le béton apportant une touche texturale à l’édifice et de grands pans vitrés reprenant la géométrie hexagonale du volume. Les appartements ont été le sujet principal de ce travail et se développent sur deux niveaux afin d’exploiter les espaces très verticaux qu’offre le silo. Ainsi, l’étage inférieur est destiné aux espaces de vie, alors que l’étage supérieur est dédié aux espaces de nuit. Le travail en façade permet également d’obtenir une dualité entre des alcôves baignées de lumière et d’autres avec une atmosphère plus intime. La spatialité est également rythmée par des grilles de poutres portant les planchers et reprenant la géométrie de l’hexagone.FARCCLABSXLSAR-DCote: 2020.010Archive: MEM.1/1 A4 vertical, archive_informatique_DDGroupe de suivi: Tombesi, Paolo (dir. pédagogique) ; Keller, Thomas (prof.) ; Serpell Carriquiry, Ricardo (maître EPFL) ; Steinmann, Martin (expert)Professeur responsable de l'Enoncé: Fivet, Corentin (ENAC IA SXL)Enoncé théorique de master: Silos helvétiques. Le potentiel d'un patrimoine
Does Lean & Agile Project Management Help Coping with Project Complexity?
No full textStill, projects in the construction sector are delivered with time delays and cost overruns. One of the reasons for poor performance was assigned to project complexity. A combination of lean construction and agile project management are hypothesized as a possible solution to cope with project complexity. In this paper we aim to understand if the implicit usage of lean and agile help coping with complexity. The research was done by means of correlation analysis on data gathered from a structured questionnaire (67 responses). In total, 51 significant correlations among 255 possible relations were found. To reduce the number of variables, factor analysis was performed. Correlation analysis on the defined factors showed 8 significant correlations among 25 relations. Several lean and agile elements were shown to significantly correlate to either reducing complexity or managing complexity. It was therefore concluded that these are promising to cope with complexity and improve project performance, which is to be confirmed in subsequent research.Integral Design & Managemen
Animal-assisted therapy using dogs: The benefits to children
No full textIncludes bibliographical references
Data deposition of 'carbon nanotubes allow capture of krypton, barium, and lead for multichannel biological x-ray fluorescence imaging'
No full textThe authors declare that all the data supporting the findings of this study (post-processing) are available within the article and its supplementary information files. Unprocessed data relating to this manuscript are available from the corresponding author upon request and XRF, TEM, Raman, XPS, TGA, NMR, and microscopy data have been deposited on the Oxford database
Alumni Association meeting in Norfolk honoring George C. Marshall, 1939
No full textAlumni Association meeting, Norfolk, Virginia, honoring George C. Marshall. 3 images. Includes Goldsborough Serpell (Class of 1895 & Board of Visitors); Robert W. Massie (Class of 1878 & Board of Visitors); Gen. George C. Marshall (Class of 1901); VMI Superintendent John A. Lejeune; Jay W. Johns (Board of Visitors); Richard Dobie (Class of 1897); Walton Walker (Class of 1909); James G. Martin IV (Class of 1932). Shown here are, left to right: Lejeune, Marshall, Dobie.3 related images
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