Classical Experimental Design Research Articles

The Threat of Terrorism and Tourist Choice Behavior

The threat of terrorism is increasingly relevant to tourism on a global scale, and no destination can claim exemption. Tourism managers need to be aware of the impact that past, current, and future terrorism events have on tourist behavior. The aim of this research is to further our understanding as to how terrorism advisory information impacts tourists’ preferences for, and trade-offs between, specific aspects of their travel. The research uses a discrete choice experiment (DCE) embedded within a classic between-subjects experimental design. US-based respondents (n = 424) completed the experiment. A random parameter logit (RPL) model is calculated to understand how tourists’ preference structures change as the threat of terrorism intensifies taking into account travel knowledge, sensation seeking, and demographic factors. Results suggest that tourist’s travel choices in relation to accommodation, independent versus group travel, cancellation policy, and price vary significantly as the threat of terrorism increases.

Pengaruh Penerapan Alat Peraga Melalui Model Pembelajaran Numbered Head Together (NHT) Terhadap Hasil Belajar Siswa Pada Materi Bangun Ruang Sisi Lengkung di Kelas IX SMP Negeri 5 Padangsidimpuan

The background of this research is the low mathematics learning outcomes of class IX students of SMP Negeri 5 Padangsidimpuan because the teacher's learning process is not able to create students 'attention, students' enthusiasm in attending classes is still low, so students have difficulty in answering mathematical problems / problems especially in wakefulness curved side space that causes student learning outcomes not to the maximum. This study aims to determine the effect of the application of teaching aids through the numbered heads together (NHT) learning model on student learning outcomes in the material to construct curved side spaces in class IX SMP Negeri 5 Padangsidimpuan. This study refers to Jerome S. Bruner's learning theory which says that learning mathematics will be more successful if the teaching process is directed at the concepts and structures made in the subject being taught, in addition to the related relationships between concepts and structures . This research is a quantitative research with an experimental method of classical experimental design. The population of this study was all students of class IX of SMP Negeri 5 Padangsidimpuan consisting of 12 classes as many as 297 students, and for the sample taken using cluster random sampling technique which is 48 students. The control class is 24 students and the experimental class is 24 students. The instrument used as a data collector is a test given twice, namely before the pretest and posttest. While for data processing and data analysis is done using the t-test formula. Based on the normality and homogeneity test both classes are normally distributed and homogeneous. The t-test is obtained from the results of hypothesis testing which shows tcount> t table, namely 10.007> 2.0129. So it can be concluded that Ho is rejected and H1 is accepted, meaning that there is a significant influence between the application of props through the numbered heads together learning model on student learning outcomes in the material to construct curved side spaces in class IX SMP Negeri 5 Padangsidimpuan.

Liquid chromatography tandem-mass spectrometry (LC-MS/MS) and dried blood spot sampling applied to pharmacokinetics studies in animals: Correlation of classic and block design

A relative bioavailability study (RBA) of two phenytoin (PHT) formulations was conducted in rabbits, in order to compare the results obtained from different matrices (plasma and blood from dried blood spot (DBS) sampling) and different experimental designs (classic and block). The method was developed by liquid chromatography tandem-mass spectrometry (LC-MS/MS) in plasma and blood samples. The different sample preparation techniques, plasma protein precipitation and DBS, were validated according to international requirements. The analytical method was validated with ranges 0.20-50.80 and 0.12-20.32 µg ml-1, r > 0.999 for plasma and blood, respectively. Accuracy and precision were within acceptance criteria for bioanalytical assay validation (< 15 for bias and CV% and < 20 for limit of quantification (LOQ)). PHT showed long-term stability, both for plasma and blood, and under refrigerated and room temperature conditions. Haematocrit values were measured during the validation process and RBA study. Finally, the pharmacokinetic parameters (Cmax, Tmax and AUC0-t) obtained from the RBA study were tested. Results were highly comparable for matrices and experimental designs. A matrix correlation higher than 0.975 and a ratio of (PHT blood) = 1.158 (PHT plasma) were obtained. The results obtained herein show that the use of classic experimental design and DBS sampling for animal pharmacokinetic studies should be encouraged as they could help to prevent the use of a large number of animals and also animal euthanasia. Finally, the combination of DBS sampling with LC-MS/MS technology showed to be an excellent tool not only for therapeutic drug monitoring but also for RBA studies.

How Asian countries understand policy experiment as policy pilots?

ABSTRACTPolicymaking based on the classical experimental design is regarded as a golden rule in the field of public policy. Despite the methodological superiority of randomized control experiment, the practices of policy experiment differ across countries, reflecting the different intentions of policymakers. This paper reviews how policy experiments are practised in Asian countries, especially Korea, China, and Singapore. As our review suggests, the term ‘policy pilot’ is preferred to ‘experiment’ as the former is considered as an exemplar proposed by the central government. At the same time, the selection of pilot sites depends on central government’s political and practical (rather than methodological) consideration. Moreover, the utilization of policy pilots does not solely depend on the success of the pilot programme or the effect size per se. As the policymaking process is a complex endeavour involving multiple streams of actors, resources, and solutions, Asian countries use policy pilot results to get ideas on how different actors respond to policy, instead of a determinant of policy decision. Therefore, we conclude that Asian countries emphasize less the rigorousness of experimental design than the possibility of pragmatic utilization of policy pilots.

Field Experiments in Organizations

Field experimentation, although rare, is the sterling-gold standard of organizational research methods. It yields the best internally valid and generalizable findings compared to more fallible methods. Reviewers in many psychology specialties, including organizational psychology, synthesize largely nonexperimental research, warn of causal ambiguity, and call for experimental replication. These calls go mostly unheeded. Practical application is a raison d'être for much organizational research. With the emergence of evidence-based management, field experiments enable us to deliver the most actionable tools to practitioners. This review explicates the role of experimental control and randomization and enumerates some of the factors that mitigate field experimentation. It describes, instantiates, and evaluates true field experiments, quasi-experiments, quasi-fields, combo designs, and triangulation. It also provides practical tips for overcoming deterrents to field experimentation. The review ends describing the merging of new technologies with classical experimental design and prophesying the bright future of organizational field experimentation.

Effects of reservoir temperature and water salinity on the swelling ratio performance of enhanced preformed particle gels

Preformed particle gel (PPG) treatment is now one of the most effective remediation techniques for conformance controlling and selective plugging of high-water flow conduits in mature water-flooded oil reservoirs. Recognizing the intrinsic properties of PPGs, e.g., the swelling ratio, in reservoir condition is of prime importance to the optimization of their performance as plugging agents. In this study, the classical and three-level full factorial experimental design methods are joined with laboratory measurements to investigate the swelling ratio dependency of a new class of enhanced PPGs at different brine salinities and reservoir temperatures. To cover severe reservoir conditions, the reservoir temperature from 298 to 418 K and brine salinity from 0 to 225,000 ppm were considered during the laboratory measurements. The results show that the swelling ratio decreases by rising water salinity. Moreover, the swelling ratio rises by increasing reservoir temperature up to 380 K and then starts to decrease. The factor screening illustrates that the swelling ratio is more dependent on salinity than the reservoir temperature in low salinity solutions, while is less dependent on salinity in high salinity solutions. In addition, a precise mathematical model was developed to predict the swelling ratio of PPGs in a wide range of salinities and temperatures. The results of this study present a practical insight into the swelling-related behavior of the PPGs at reservoir conditions.

Stress Testing of Quetiapine Fumarate by a Chemometric Assisted Multi-Component Ion-Interaction System

Classical experimental designs have been popularly employed in establishing robust analytical methods while achieving other advantages, viz., reduction in the number of experiments and hence lower reagent consumption and less laboratory work. To achieve optimum chromatographic condition, a computer-aided Box-Behnken Design (BBD) in ion-pairing stability-indicating RP-HPLC assay of quetiapinefumarate along with its stress related substances has been investigated here, proving to be an invaluable tool in ascertaining a reliable method. The study includes forced degradation of quetiapinefumarateunder acidic, alkaline, photo, oxidative and peroxide stress conditions followed by separation of degradation products. Critical factors including buffer pH, % organic phase (acetonitrile) and concentration of hexane sulphonate (ion-pairing reagent) susceptible to influence the separation (critical resolutions) and total analysis time were investigated by response surface methodology. The best optimal separation condition as obtained was observed on an enable C-18 column (250mm x 4.6mm i.d, 5μm particle size) using mobile phase composed of Phosphate buffer (pH 2.0) containing 0.002mM hexane sulphonate and acetonitrile (74.4:25.6 v/v) at a flow rate of 1.00ml/min. The eluents were observed at 220nm using a PDA detector. Further, the method was validated to ensure its reliability and other regulatory criteria are met.

Efficacy of Combination of Motivational Interviewing and Cognitive Behavior Intervention with Substance Abuse Street Adolescents in India: A Randomized Control Study

This study assessed the efficacy of a 4-month program combining motivational interviewing and cognitive behavior intervention on substance-using street adolescents in India. The study followed classical experimental design and the subjects were randomly assigned to control and experimental groups. Readiness to change questionnaire and Adolescent Relapse Coping Questionnaire tools were used for the evaluation of the intervention program. At the baseline, majority of the respondents in both the groups were at the precontemplation stage of motivation. At the end of the 3rd month of the intervention, there was a significant difference, χ2 = 31.139, df = 2, p < .001, between the 2 groups on the stages of motivation. The study’s limitations are noted.

Transporting established insights from classical experimental design, implemented using methods that rely on modern computing to address causal questions in environmental epidemiology

Transporting established insights from classical experimental design, implemented using methods that rely on modern computing to address causal questions in environmental epidemiology

Armentum: a hybrid direct search optimization methodology

Design of experiments (DOE) offers a great deal of benefits to any manufacturing organization, such as characterization of variables and sets the path for the optimization of the levels of these variables (settings) trough the Response surface methodology, leading to process capability improvement, efficiency increase, cost reduction. Unfortunately, the use of these methodologies is very limited due to various situations. Some of these situations involve the investment on production time, materials, personnel, equipment; most of organizations are not willing to invest in these resources or are not capable because of production demands, besides the fact that they will produce non-conformant product (scrap) during the process of experimentation. Other methodologies, in the form of algorithms, may be used to optimize a process. Known as direct search methods, these algorithms search for an optimum on an unknown function, trough the search of the best combination of the levels on the variables considered in the analysis. These methods have a very different application strategy, they search on the best combination of parameters, during the normal production run, calculating the change in the input variables and evaluating the results in small steps until an optimum is reached. These algorithms are very sensible to internal noise (variation of the input variables), among other disadvantages. In this paper it is made a comparison between the classical experimental design and one of these direct search methods, developed by Nelder and Mead (1965), known as the Nelder Mead simplex (NMS), trying to overcome the disadvantages and maximize the advantages of both approaches, trough a proposed combination of the two methodologies.

Dynamic Response Surface Models: A Data-Driven Approach for the Analysis of Time-Varying Process Outputs

In a recent publication (Ind. Eng. Chem. Res. 2013, 52 (35), 12369) we generalized the classic design of experiments (DoE) methodology by introducing the Design of Dynamic Experiments (DoDE), allowing for the systematic design of experiments involving time-varying inputs. Here, we expand the response surface model (RSM) methodology, used in DoE and DoDE problems, so that it describes the time-evolution of the process, not just the results at the end of the experiment. We apply this generalized type of RSM model, to be denoted by DRSM, to three example processes; a nonisothermal batch reactor with a simple reaction, an isothermal semibatch reactor with several reactions, and a semibatch penicillin fermentation process. Using a limited number of online measurements at prespecified equidistant time instants, we are able to quickly and accurately represent the time evolution of the process output through these simple interpolative data-driven models. The ever-increasing availability of time-resolved measureme...

Bayesian analysis of definitive screening designs when the response is nonnormal

Definitive screening designs (DSDs) are a class of experimental designs that allow the estimation of linear, quadratic, and interaction effects with little experimental effort if there is effect sparsity. The number of experimental runs is twice the number of factors of interest plus one. Many industrial experiments involve nonnormal responses. Generalized linear models (GLMs) are a useful alternative for analyzing these kind of data. The analysis of GLMs is based on asymptotic theory, something very debatable, for example, in the case of the DSD with only 13 experimental runs. So far, analysis of DSDs considers a normal response. In this work, we show a five‐step strategy that makes use of tools coming from the Bayesian approach to analyze this kind of experiment when the response is nonnormal. We consider the case of binomial, gamma, and Poisson responses without having to resort to asymptotic approximations. We use posterior odds that effects are active and posterior probability intervals for the effects and use them to evaluate the significance of the effects. We also combine the results of the Bayesian procedure with the lasso estimation procedure to enhance the scope of the method. Copyright © 2016 John Wiley &amp; Sons, Ltd.

A Fast and Scalable Method for A-Optimal Design of Experiments for Infinite-dimensional Bayesian Nonlinear Inverse Problems

We address the problem of optimal experimental design (OED) for Bayesian nonlinear inverse problems governed by partial differential equations (PDEs). The inverse problem seeks to infer an infinite-dimensional parameter from experimental data observed at a set of sensor locations and from the governing PDEs. The goal of the OED problem is to find an optimal placement of sensors so as to minimize the uncertainty in the inferred parameter field. Specifically, we seek an optimal subset of sensors from among a fixed set of candidate sensor locations. We formulate the OED objective function by generalizing the classical A-optimal experimental design criterion using the expected value of the trace of the posterior covariance. This expected value is computed through sample averaging over the set of likely experimental data. To cope with the infinite-dimensional character of the parameter field, we construct a Gaussian approximation to the posterior at the maximum a posteriori probability (MAP) point, and use the...

SAMPLING THE SPATIAL HETEROGENEITY OF THE HONEYCOMB MODEL IN MAIZE AND WHEAT BREEDING TRIAS: ANALYSIS OF SECONDARY DATA COMPARED TO POPULAR CLASSICAL DESIGNS

SUMMARYThe systematic rather than random entry arrangement of honeycomb designs (HDs) has been deployed to sample the spatial heterogeneity. This hypothesis was studied in fairly homogeneous populations, assuming that their phenotypic variability stemmed absolutely from spatial rather than genetic heterogeneity. It was based on single plant performance in two separate trials of a maize hybrid and a wheat cultivar reflecting different level of spatial heterogeneity. In general, the HDs counteracted spatial heterogeneity well, particularly when the number of evaluated entries was limited. There was a suggestion that they do well even in a high number of entries with many replicates per entry. Distribution and layout of spatial heterogeneity across the experimental area did not affect the precision of the HDs. Standardized configuration, which ensures implementation of essential principles met in other experimental models such as blocking, replication and nearest-neighbour (NN) adjustment on the same baseline, renders the honeycomb experimental pattern advantageous over the classical experimental designs like the randomized complete block (RCB), the NN method and the lattice model.

Analysis of Design of Experiments with Dynamic Responses

Multivariate understanding offers information that is critical to the successful evaluation of risk within a pharmaceutical process. A common means to acquire such data in the absence of detailed prior knowledge is a design of experiments (DoE). A significant challenge in the implementation of conventional DoE methodology is the analysis of processes with transient responses. A large number of processes in the pharmaceutical industry are described by kinetic processes which results in severe difficulties in the interpretation of the DoE analysis. In this paper we describe a workflow utilizing classic DoE practices, data visualization, and techniques extracted from the larger field of machine learning to facilitate the interpretation of DoE results in process development. The resulting analysis is appropriate for use in surveying the knowledge space for a chemical reaction and identifying areas of risk that merit verification. For clarity the workflow is described using a numerical solution to a well-defin...

The impact of writing training on transediting in translation, analyzed from a product and process perspective

This paper reports on a quasi-experimental study of the effect of writing training on transediting in the translation product and process of undergraduate translation students. A classical pretest-posttest experimental design was used, in which the experimental group was trained in writing instructive texts in their mother tongue (Dutch) and the control group received a placebo training. Over the course of the experiment, both groups translated four Spanish instruction manuals into Dutch. The source texts contained a number of rich points that could not be translated literally into the target language and consequently required transediting. The product data indicated that writing training led to a higher amount and quality of transediting, specifically of macro-textual features. The process data showed that the participants of the experimental group based their decision to transedit on more diverse and precise criteria than the control group. Writing training also yielded a more detailed understanding of the acceptability norms of instruction manuals and led to a more critical stance towards the source text. Writing training did not influence the moment of transediting, which was mostly carried out as a first translation solution.

Analysing the effect of stand density and site conditions on structure and growth of oak species using Nelder trials along an environmental gradient: experimental design, evaluation methods, and results

Most current approaches in forest science and practice require information about structure and growth of individual trees rather than - or in addition to - sum and mean values of growth and yield at forest stand level as provided by classic experimental designs. By inventing the wheel design, Nelder provided the possibility to turn to the individual tree as basic information unit. Such trials provide valuable insights into the dependency of growth on stand density at particular sites. Here, we present an extension of the original design and evaluation by Nelder. (i) We established Nelder wheels along an environmental gradient through Europe in atlantic climate in Belgium and Germany, Mediterranean climate in Italy, continental climate in Hungary as well as on high land climate in Mexico. Such disjunct Nelder wheels along an environmental gradient can be regarded and analysed as a two-factor design with the factors of site condition and stand density. (ii) We present an advanced statistical approach to evaluate density dependent growth dynamics of trees planted in form of the Nelder design, which considers spatio-temporal autocorrelation. (iii) We prove the usefulness of the methods in improving ecological theory concerning density related productivity, trade-offs between facilitation and competition, and allometric relations between size variables. First evaluations based on remeasured Nelder wheels in oak (Quercus robur L.) show a size growth differentiation during the first observation period. In particular, height growth is accelerated under higher competition indicating facilitation effects. We detect furthermore a high variability in allometric relations. The proposed design, methods, and results are discussed regarding their impact on forest practice, model building, and ecological theory. We conclude that the extended Nelder approach is highly efficient in providing currently lacking individual tree level information.

Improving Service Utilization for Parents with Substance Abuse Problems: Experimenting with Recovery Coaches in Child Welfare

Substance abusers often face substantial systematic and personal barriers to receiving required substance abuse treatment services as well as other services; hence, various linkage mechanisms have been proposed for drug abuse treatment programs to overcome such barriers. Although there is a growing interest in the use of case management with a substance abuse background, its effectiveness in child welfare has yet to be explored. In this study the author attempts to investigate the effectiveness of case management in service utilization by systematically evaluating the five-year Alcohol and Other Drug Abuse (AODA) waiver demonstration project with Recovery Coaches in Illinois. A classic experimental design with a control group was used. Random assignment occurs at the agency level. Parents in the experimental group (N = 1562) received recovery coaches in addition to traditional child welfare services while parents in the control group (N = 598) only received traditional child welfare services. Bivariate and multivariate analyses (Ordinary Last Square regressions) were used. Compared to parents in the control group, parents in the experimental group were more likely to utilize substance abuse treatment. The results suggest that gender, education level, employment status, and the number of service needs were significantly associated with service utilization. Controlling other factors, recovery coaches improved overall service utilization. Because the outcome of child welfare often depends on the improvement of risks or resolution, it is important for parents to utilize the needed services. Future studies need to address what aspects of recovery coaches facilitate the services utilization.

New easy handling and sampling device for bioavailability screening of topical formulations.

Biopharmaceutical assessment of topical drug formulations is widely carried out by using vertical diffusion cells (Franz type cell). Although Franz diffusion cell model is well designed for percutaneous absorption studies, the extent of drug penetration within the skin requires more adapted device. Recently, we have developed a new patented versatile, easy-to-use, and disposable diffusion cell called VitroPharma. In this study we have assessed the cutaneous bioavailability of caffeine as hydrophilic compound model using Franz diffusion cell and VitroPharma. The percutaneous absorption of caffeine assessed with Franz diffusion cell and VitroPharma was characterized by using (i) finite dose model and (ii) classical pharmacokinetic analysis. Furthermore, the follow-up of caffeine penetration within the skin was determined by sequential measurements of tissular drug concentration throughout the time of skin exposure with VitroPharma. However, classical experimental design using Franz diffusion cell involved unique determination of tissular concentration at the final point of skin exposure protocol. Finally, device equivalence between Franz diffusion cell and VitroPharma was claimed from percutaneous absorption data analysis. Concomitant assessment of dual penetration and permeation kinetics by using VitroPharma reinforced the understanding of skin drug delivery.

Tracking markers of response inhibition in electroencephalographic data: why should we and how can we go beyond the N2 component?

Response inhibition is a pivotal component of executive control, which is especially difficult to assess. Indeed, it is a substantial challenge to gauge brain-behavior relationships because this function is precisely intended to suppress overt measurable behaviors. A further complication is that no single neuroimaging method has been found that can disentangle the accurate time-course of concurrent excitatory and inhibitory mechanisms. Here, we argue that this objective can be achieved with electroencephalography (EEG) on some conditions. Based on a systematic review, we emphasize that the standard event-related potential N2 (N200) is not an appropriate marker of prepotent response inhibition. We provide guidelines for assessing the cortical brain dynamics of response inhibition with EEG. This includes the combined use of inseparable data processing steps (source separation, source localization, and single-trial and time-frequency analyses) as well as the amendment of the classical experimental designs to enable the recording of different kinds of electrophysiological activity predicted by different models of response inhibition. We conclude with an illustration based on recent findings of how fruitful this approach can be.