Improved Measured Mile Analysis Technique

Quantifying lost labor productivity on construction projects is difficult and sometimes subjective. A widely accepted way to quantify losses is the “measured mile” approach. It compares periods of a project that have been impacted by change to those that have not been impacted. As currently practiced the measured mile relies on subjectively identifying that reference period. In this paper the measured mile and a variant, the baseline method, are analyzed and compared to a new, proposed statistical clustering method. This new approach is advocated because it determines its reference period using objective criteria. A case study is included to show how the three methods work, and advantages and disadvantages of each method are presented in this paper.     

Baseline Determination in Construction Labor Productivity-Loss Claims

Various ways of quantifying damages have been applied to productivity loss claims in construction. All of the ways attempt to be as objective as possible based on the extent of information available in a particular case. The measured mile, a widely accepted method, is employed when an unimpacted baseline period of production can be identified. Although that approach is considered to be the most objective method available in such cases, the method is limited and does not directly account for variation in individual productivity values about a normal or natural level of productivity. A gap exists between the use of existing methods and the availability of an appropriate methodology that specifically addresses variation in productivity. The key lies in the way baseline productivity is measured, which is inherently statistical, yet no truly statistical methods are used to establish such a baseline. Using the measured mile as a backdrop, this article provides an objective, measurement-based approach that can be used to establish a productivity baseline applied to construction productivity loss claims, based on the application of statistical methods aided by a process control chart. The focus is on providing the basic principles and concepts underlying the approach presented.     

Case Law and Variations in Cumulative Impact Productivity Claims

Proving and quantifying lost productivity due to cumulative impacts of multiple changes are difficult tasks. This paper presents the most acceptable methods from case law and demonstrates their applications for analyzing the loss of productivity. These methods include earned value analysis, measured mile analysis, and combinations of these two. They are either well established or drawn from recent court and board decisions. A case study is used to illustrate and compare the use of these methods. These methods result in considerably different loss of productivity values though the actual amount (i.e., inefficiency in labor hours) is unique for a particular case and though these methods are often thought to be similar or even the same. How a measured mile analysis and its variants are employed affects the amount of lost productivity estimated. The variants can avoid some drawbacks of measured mile and earned value studies. Nevertheless, which method is more accurate and reliable is difficult to provide for a particular claim. Practitioners should choose between them based on the availability of project records and the nature of changes and cumulative impacts. Practitioners may also employ two or more methods to perform a “sensitivity analysis” of the chosen methods and persuade the other party and/or the jury that their estimate of lost productivity is sufficiently certain.     

The changes of lipids, lipoproteins and apolipoproteins in plasma in ischemic stroke

Contents of lipids (cholesterol CS, triglycerides) as well as levels of CS of lipoproteins of different density and of apolipoproteins A1 and B were measured in blood serum of 31 patients in different periods after of ischemic stroke. The majority of the indices studied were significantly decreased in men in acute periods of the stroke, especially in 8-21 days after the stroke development. Meanwhile, the levels of lipids, CS lipoproteins of both low and very low densities were increased later. Contents of CS of antiatherogenic lipoproteins of high density (HDLP) was low in different periods after the development of disorders of cerebral circulation. This confirms the concept that low level of HDLP is one of the risk factors of ischemic stroke. Decrease of the levels of both lipids and CS of lipoproteins of different density was more pronounced in patients with more severe atherosclerotic damages of the main cerebral arteries. Disorders of metabolism of lipoproteins in ischemic disorders of cerebral circulation are discussed with reference to literary data taking into consideration their heterogeneity. Genetically determined pathology of certain apolipoproteins plays a key role factor in the development of early atherosclerosis and in the elucidation of biochemical markers of the primary damages of cerebral vessels.     

A logistic model for trend in 2 x 2 x kappa tables with applications to meta-analyses

There recently has been an increased interest in examining the relationship between the baseline (control) risk of an adverse outcome and the magnitude of the treatment effect (Brand and Kragt, 1992, Statistics in Medicine 11, 2077-2082; Davey Smith, Song, and Sheldon, 1993, The British Medical Journal 306, 1367-1373; Senn, 1994, Statistics in Medicine 13, 293-294). To facilitate such an examination, we propose a logistic model in which the relationship between the treatment effect, as measured by the log odds ratio, and the baseline risk is specified parametrically. This procedure is founded on a product-binomial likelihood and generates maximum likelihood estimates of the baseline event rates and two parameters characterizing the trend in the treatment effect. We fit this model to data from a meta-analysis involving the treatment of women at risk of preterm labor and contrast our findings with those of an earlier analysis.     

Assessing program effects in the presence of treatment—baseline interactions: A latent curve approach.

Methods for assessing treatment effects of longitudinal randomized intervention are considered. The focus is on modeling the nonlinear relationship between treatment effects and baseline often observed in prevention programs designed for at-risk populations. Piecewise linear growth modeling was used to study treatment effects during the different periods of development. A multistep multiple-group analysis procedure is proposed for assessing treatment effects in the presence of nonlinear treatment-baseline interactions. Standard errors of the estimates from this multistep procedure were obtained using a bootstrap approach. The methods are illustrated using data from the Johns Hopkins Prevention Research Center involving an intervention aimed at improving classroom behavior. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Labor Productivity Drivers and Opportunities in the Construction Industry

The study of labor productivity in the construction industry is gaining increasing attention as the industry faces multiple problems related to its workforce. This paper presents the results of a survey instrument applied to determine the relative level of relevance of construction labor productivity drivers and opportunities. Owners, general contractors, electrical contractors, mechanical contractors, consultants, and others participated in this survey. Management skills and manpower issues were identified as the two areas with the greatest potential to affect productivity according to survey respondents. Surprisingly, external factors, which are often cited as a major cause for reduced productivity in the construction industry, were considered to be one of the least relevant productivity drivers. These results suggest that respondents consider the improvement of labor productivity within their reach and control rather than determined by external conditions.     

Psychological autopsy: Scientific psychohistory or clinical intuition?

Discusses deficiencies in both the concept and actual practice of psychological autopsy (PA). Identification of these deficiencies is essential to determine whether the procedure should be retained and, if so, how it can be improved. As an organized method of investigation, PA is in its infancy. Defined procedures and criteria are necessary to prevent premature and equivocal expiration of PA. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Movie exposure to smoking cues and adolescent smoking onset: A test for mediation through peer affiliations.

Objective: To determine whether the effect of movie exposure to smoking on adolescent smoking onset is mediated through increased affiliation with peers who smoke. Design: A longitudinal study was conducted with a sample of 5th- 8th graders; persons who were nonsmokers at the baseline assessment (N = 2,614) were followed up 18 months later. Movie exposure to smoking cues was assessed at baseline with a rigorous coding procedure. Main Outcome Measure: A school-based survey and follow-up telephone interview determined whether the participant smoked cigarettes. Results: Longitudinal structural modeling analysis indicated movie-smoking exposure was related to smoking onset both through an indirect effect involving increased affiliation with peer smokers and through a direct effect. The analysis controlled for demographics, parenting style, rebelliousness and sensation seeking, school performance, parental smoking, and sibling smoking; several of these variables also had mediated or direct effects to smoking onset. Conclusion: The effect of movie exposure on adolescent smoking onset is attributable in part to a social mechanism. Implications of media effects for prevention are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Stability Analysis of Complex Soil Slopes using Limit Analysis

The limit equilibrium method is commonly used for slope stability analysis. Limit equilibrium solutions, however, are not rigorous because neither static nor kinematic admissibility conditions are satisfied. Limit analysis takes advantage of the lower- and upper-bound theorems of plasticity theory to provide rigorous bounds on the true solution of a stability problem. In this study, finite-element models are used to construct both statically admissible stress fields for lower-bound analysis and kinematically admissible velocity fields for upper-bound analysis of soil slopes. While limit analysis of relatively simple slopes, typically homogeneous and of simple geometry, has been done previously, limit analysis of slopes with complex geometries, soil profiles, and groundwater patterns could not be effectively done in the past. In this paper, the theoretical basis and procedure for limit analysis of such slopes is presented. Various examples of slopes are selected from the literature and analyzed using both limit equilibrium and limit analysis. Factors of safety from limit equilibrium and limit analysis are compared. A comparison is also made, for each example, between the critical slip surfaces from limit equilibrium with the velocity field and plastic zone from the upper-bound solution and with the stress field from the lower-bound solution.     

Is textbook knowledge of ultrasonography also valid in emergency admission?

Textbook knowledge of sonography is not immediately applicable in emergencies where the favourable prerequisites characterizing the standard case are often lacking. The question therefore arises of what textbook knowledge is also viable in the average emergency unit, under what circumstances and for which clinical questions. The answer to this differentiated question is a graded concept with "primary emergency sonography", "extended" and "standard sonography". The indications and advantages of "primary emergency sonography" in contrast to standard procedure are discussed in detail. The key to success depends on meticulous introduction and training, strict compliance with indications and principle, and rigorous surveillance by an experienced ultrasonic specialist. In addition further scientific examination of the concept is necessary.     

Evaluation of Surficial Stability for Homogeneous Slopes Considering Rainfall Characteristics

Shallow slope failures in residual soil during periods of prolonged infiltration are commonly occurring in the world. This study examines an infinite slope analysis to estimate the influence of infiltration on surficial stability of slopes by the limit equilibrium method. An approximate method that accommodates the boundary condition of a uniform rainfall has been proposed to evaluate the likelihood of shallow slope failure that is induced by a particular rainfall event. The method based on the Mein and Larson model, which provides an explicit solution for preponding infiltration, has been applied to various types of soil having measured unsaturated hydraulic properties. To compare results with those obtained from the approximate method, a series of numerical analyses were carried out. According to the results, with the use of properly estimated input parameters, the approximate method was found to give results that compare reasonably well with those of more rigorous finite element analyses.     

Completion rates in health-related quality-of-life assessment: approach of the National Cancer Institute of Canada Clinical Trials Group

The approach of the National Cancer Institute of Canada Clinical Trials Group to measuring compliance, that is, completion rates, for health-related quality of life questionnaires is presented. Completion rates can be measured at the institutional, patient, questionnaire and item levels for baseline, on-treatment and off-treatment follow-up study periods. Time windows are defined for each expected completion time. In seven completed clinical trials, completion rates were high with more than 93 per cent of patients completing questionnaires in the specified time windows at baseline and while on-treatment. The rate while on off-treatment follow-up is still acceptable at 85 per cent. The proportions of analysable questionnaires were 97.6 per cent, 82.0 per cent and 77.0 per cent respectively, at the three study periods. Item completion rates within questionnaires were high at 95.5 per cent or more. The variables most likely to influence baseline and on-treatment questionnaire completion rates were breast cancer, ovarian cancer, metastases and study centre size.     

Identification of Concentrated Damages in Euler-Bernoulli Beams under Static Loads

An identification procedure of concentrated damages in Euler-Bernoulli beams under static loads is presented in this work. The direct analysis problem is solved first by modeling concentrated damages as Dirac’s delta distributions in the flexural stiffness. Closed-form solutions for both statically determinate and indeterminate beams are presented in terms of damage intensities and positions. On this basis, for the inverse damage identification problem, a nonquadratic optimization procedure is proposed. The presented procedure relies on the minimization of an error function measuring the error between the analytical model response and experimental data. The procedure allows to recognize “a posteriori” some sufficient conditions for the uniqueness of the solution of the damage identification problem. The influence of the instrumental noise on the identified parameters is also explored.     

Exponential Formula for Bedload Transport

An exponential formula that does not involve the concept of the critical shear stress is derived in this study for computing bedload transport rates. The formula represents well various experimental data sets ranging from the weak transport to high shear conditions. Comparisons of the present study are also made with many previous bedload formulas commonly cited in the literature.     

Validity of Uniform Flow Hypothesis in One-Dimensional Morphodynamic Models

Local-uniform-flow (LUF) hypothesis is a simplification of the governing equations describing river morphodynamics, which is needed to determine the evolution of the bed profile and bed-material composition in the case of large time and space scales. This paper presents a rigorous analysis of the full one-dimensional river hydrodynamic and morphodynamic mathematical model compared to its LUF approximation. The analysis establishes two criteria to assess the validity of the LUF hypothesis: (1) a criterion for rivers in equilibrium and (2) a criterion for evolving rivers (i.e., in nonequilibrium). The first criterion is based on the concept of the morphological box. Variations of the river bed longer than the box length are adequately reproduced by the LUF hypothesis, whereas only spatially averaged values are resolved within the box. The second criterion is based on the concept of an evolution window. Temporal variations represented by wave periods larger than the evolution window can be adequately reproduced by the LUF hypothesis, whereas variations with shorter periods are averaged within this window. The minimum size of morphological box and evolution window that limit the error introduced by the LUF hypothesis increases when the Froude number decreases. Further, the minimum size of the evolution window increases for decreasing sediment concentration and increasing mixing layer thickness (i.e., for larger bed forms). The LUF hypothesis is therefore best applied to small mountain rivers for which both the minimum size of the morphological box and the evolution window is relatively small, so that spatial and temporal variations can be resolved in more detail. Applications using the LUF hypothesis for large watersheds (including the lowland portion of the fluvial network) are possible, but are limited to simulations over larger spatial and temporal intervals.     

Validation of thermography in the diagnosis of reflex sympathetic dystrophy

OBJECTIVES: To examine the validity of several thermogram-derived indices of autonomic functioning in the diagnosis of reflex sympathetic dystrophy (RSD). DESIGN: A series of chronic pain patients were classified diagnostically based on thermogram results using discriminant function analysis, and validity measures (e.g., sensitivity, specificity) were used to determine the accuracy of computerized thermographic pixel analysis in discriminating RSD from other pathology. SETTING: The study was conducted at the Rush Pain Center, a multidisciplinary outpatient pain clinic. PATIENTS: A series of 46 chronic pain patients referred for suspected sympathetically mediated pain. INTERVENTIONS: All patients underwent computerized thermographic examination under a baseline condition after acclimating to a climate-controlled room, immediately after a cold challenge was applied to the contralateral uninvolved extremity (4 degrees C for 90 s) and 20 min after the cold challenge. OUTCOME MEASURES: Temperature during the three experimental periods, degree of temperature asymmetry between affected and nonaffected limbs during the three periods, response to cold challenge, and recovery following cold challenge were measured. RESULTS: Temperature asymmetry accurately discriminated between RSD and non-RSD patients, with the most accurate asymmetry measures obtained at baseline. Responses to cold challenge and actual temperature values did not discriminate between RSD and non-RSD pain patients. CONCLUSIONS: Thermography can be a useful component of RSD diagnosis. In situations where sensitivity and specificity are equally important, an asymmetry cutoff of 0.6 degree C appears optimal. If specificity (i.e., accurately ruling out non-RSD cases) is more important, a cutoff of 0.8 degree C or 1.0 degree C may be considered as well.     

Respective influence of occupational and personal factors on respiratory function in dairy farmers

OBJECTIVE: This study proposes to test the hypothesis that early loss of a parent, coupled with poor quality family relationships, would result in long-term increased cardiovascular and cortisol reactivity to stress. METHODS: Subjects included 30 university students who lost one parent before age 16, and 31 control subjects. Blood pressure (BP) was measured continuously during 5-minute baseline and recovery periods, and during each of 2 tasks--viewing a 7-minute video clip depicting the death of a parent, and giving a 3-minute impromptu speech (1-hour rest between tasks). Salivary cortisol samples were collected immediately before each task, and at 5 and 20 minutes posttask. Quality of family relationships (FR) was measured using the Moos Family Environment Scale. RESULTS: Repeated-measures analysis of covariance revealed significant main effects on BP of both parental loss and FR for both tasks (all p values < .05) such that subjects who lost a parent or reported poor quality FR showed higher BP across all periods. The loss by FR by period interaction was not significant. An FR by period interaction was found for cortisol during the movie, in which poor quality FR subjects showed increased cortisol, whereas all others showed decreases. A loss by period interaction was found for cortisol during the speech, in which cortisol increased in loss subjects and decreased in non-loss subjects. CONCLUSIONS: These findings indicate that both childhood loss of a parent and poor quality of caretaking are associated with long-term increases in BP and altered neurohormonal responses to stress.     

Can Labor Inputs be Measured and Controlled Automatically?

Real-time control of on-site construction is a growing field still in its infancy. Labor inputs is an important project performance indicator to be controlled because it is a leading input in construction projects. A model for automated control was developed and verified in the field, to demonstrate that labor inputs can be automatically measured and controlled. The concept behind this development is that indirect data—workers’ locations measured automatically at regular time intervals—can be collected automatically and converted into labor inputs using computerized algorithms. The model was implemented in a concept-proving prototype, which was applied in three construction projects to verify the concept and test the feasibility of developing a full-scale prototype. The encouraging results of the field experiments showed that it is possible to convert worker’s locations automatically measured at regular time intervals into labor inputs, and thus automatically control them. The expected accuracy of such a system is ±10–20%. Additional work is currently underway to develop a location measurement system and other components of the full-scale prototype.     

Reconciling conflicting results derived from experimental and survey studies of attitude change.

"Two quite different types of research design are characteristically used to study the modification of atitudes through communication. In the first type, the experiment, individuals are given a controlled exposure to a communication and the effects evaluated in terms of the amount of change in attitude or opinion produced… . In the alternative research design, the sample survey, information is secured through interviews or questionnaires, both concerning the respondent's exposure to various communications and his attitudes and opinions on various issues." Divergences in results from the 2 methods are cited and the reconciliation of apparent conflicts is attempted. There appear to be "certain inherent limitations of each method." The mutual importance of the 2 approaches to communication effectiveness is stressed. "… each represents an important emphasis. The challenge of future work is one of fruitfully combining their virtues so that we may develop a social psychology of communication with the conceptual breadth provided by correlational study of process and with the rigorous but more delimited methodology of the experiment." 24 refs (PsycINFO Database Record (c) 2010 APA, all rights reserved)