A Confounder is a variable whose presence affects the variables being studied so that the results do not reflect the actual relationship. There are various ways to exclude or control confounding variables including Randomization, Restriction and Matching. But all these methods are applicable at the time of study design. When experimental designs are premature, impractical, or impossible, resear...

Although common in the educational and developmental areas, multilevel models are not often utilized in the analysis of data from experimental designs. This article illustrates how multilevel models can be useful with two examples from experimental designs with repeated measurements not involving time. One example demonstrates how to properly examine independent variables for experimental stimu...

In this Data in Brief paper, a central composite experimental design was planned to collect the surface roughness of an end milling operation of AISI 1045 steel. The surface roughness values are supposed to suffer some kind of variation due to the action of several factors. The main objective here was to present a multivariate experimental design and data collection including control factors, n...

nanocrystalline ceria has been considered as support for carbon monoxide preferentially oxidation. in this study ceria was prepared by precipitation method and the effects of preparation conditions, such as ph of solution (8-10), aging time (1-12 hr), drying temperature (80-120 °c), calcination time (2-6 hr) and temperature (400-600 °c) were investigated on ceria synthesized powders properties....

We present a novel experimental scheme for two-dimensional fluorescence-detected coherent spectroscopy (2D-FDCS) using a non-collinear beam geometry with the aid of "confocal imaging" of dynamic (population) grating and 27-step phase-cycling to extract the signal. This arrangement obviates the need for distinct experimental designs for previously developed transmission detected non-collinear tw...

We compute the posterior distributions of the initial population and parameter of binary branching processes, in the limit of a large number of generations. We compare this Bayesian procedure with a more näıve one, based on hitting times of some random walks. In both cases, central limit theorems are available, with explicit variances.

Experimentation is a powerful methodology that enables scientists to empirically establish causal claims. However, one important criticism is that experiments merely provide a black-box view of causality and fail to identify causal mechanisms. Specifically, critics argue that although experiments can identify average causal effects, they cannot explain the process through which such effects com...

there have been many productive methods developed so far for optimization of multiple response surface (mrs) problems. this paper tends to review the most seminal approaches in mrs and discuss the strength and weakness of each of the approaches through existing aspects in mrs. a numerical example is included to compare results by different methods. finally some of the prominent areas for future...

the taguchi design of experiments was used to test the relative importance of medium components and environmental factors on poly(β-hydroxybutyrate)(phb) production by ralstonia eutropha. the optimum condition was obtained as: fructose concentration, 15 g/l; c/n ratio, 7.4; agitation speed 200 rpm; culture time, 40 h; temperature, 25 ° c; seed age, 15 h. at optimum condition the yield of phb pr...

in this work, boehmite sol was prepared by a previously applied and validated method; hydrolysis of aluminum chloride hexa-hydrate. in order to obtain precise results, the effect of ph after adding precipitating agent, aging time, peptizing temperature and ultrasonic vibration time on the crystallite size of final precipitate were investigated in a narrow range. the preparation conditions appli...