All Factored Together

The one-factor-at-a-time method (which is in itself an experimental design) is inefficient, can give misleading results, and in general it should be avoided. In the vast majority of cases our approach will be to vary all factors together. 

Avoid putting all factors together and adopt the method of pairwise comparison. 

Systems in which it is easy to make an error should be avoided. To reduce the risk of contaminated product and reworked batches, it is generally better to avoid bringing several chemicals together in a manifold. However, manifolding can be done safely and it may be the best design when all factors are considered. 

Project management also influences the likelihood that staffing levels wiU be adequate for the tasks required. This latter factor, together with the extent to which appropriate jobs are assigned to individuals, and the complexity of the jobs, all influence the level of time pressure likely to be felt by the operator. The detailed calculations, which show how the probability of human error is influenced by changes in the sociotechnical factors in the situation, are given in Appendix 5A. 

In summary, a practical realization of FEDs for the pure electrostatic detection of charged macromolecules by their intrinsic molecular charge, especially in high ionic-strength solutions such as physiological conditions, seems to be problematic. All the above discussed disturbing factors, together with a possible undesired adsorption or... 

You have thought about the what, where, when, and how now you need to put all four factors together to build your study plan. Your study plan should be as detailed and specific as possible. When you have created your study plan, you then need to follow through. 

Irrespective of the risk, assumptions and decisions will have to be made because of uncertainty. Implications of attempting to characterize all variability and uncertainty in the risk assessment need to be considered. For example, exaggerating uncertainties can obscure the scientific basis of risk management decisions, leaving the impression that the decision has been arbitrary in nature (NRC 1989). The purpose of the uncertainty factor together with the type of assessment (e.g., deterministic or probabilistic, protective or best estimate) must be clearly communicated. Uncertainty factors can be described in 3 categories ... 

Table 5.17 shows a complete report for the effect of all factors on the plate count. The overall relative standard deviation is displayed to give an estimate of the overall size of variations observed when all factors change together. 

Risk is a complex, multi-dimensional concept. Evidence from social research on attitudes to risk suggest that in assessing a risk, people (including experts) tend to run all the different factors together the expected benefits as well as the harms who takes the decisions what is put at risk whether they have any agency in the risky situation to avoid the possible harm whether the harm is something that can be remedied or coped with. 

All these factors together mean enhanced accuracy and speed. 

In order to increase the efficiency further, it is helpful to use any available knowledge about the simulated real system to keep similar factors together. For example, we group together all test yield factors and conjecture that, if one... 

The frictional properties of molybdenum disulphide films have been discussed in the previous two chapters, and it is not necessary to repeat the same information here. However, before proceeding to discuss the influence of various factors on the magnitude of the friction, it may be worth emphasizing the fact that friction varies with the gaseous environment, humidity, temperature, load, purity and the state of orientation and consolidation of a film. No-one has ever attempted the huge task of carrying out a parametric study of all these factors together, and most of the published work has failed to define one or more of the influential conditions. As a result it is very difficult to establish absolute values of the coefficient of friction in any particular situation. 

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