Dynamic allocation

Dynamic randomisation - minimisation When there are a large number of prognostic variables to account for, it may be practically difficult to implement a fully stratified randomisation scheme. The reason being that with a large number of factors there are even more individual stratum combinations and therefore there will be very few patients in many of the combinations. In such circumstances the method of dynamic allocation, or minimisation, has been recommended. 

It allows the implementation of more complex allocation schemes such as minimisation and dynamic allocation. 

Dynamic aibcation is an alternative procedure in which the allocation of treatment to a subject is influenced by the current balance of allocated treatments and, in a stratified trial, by the stratum to which the subject belongs and the balance within that stratum. Deterministic dynamic allocation procedures should be avoided and an appropriate element of randomisation should be incorporated for each treatment allocation. ... 

Dynamic allocation moves away from having a pre-specified randomisation list and the allocation of patients evolves as the trial proceeds. The method looks at the current balance, in terms of the mix of patients and a number of pre-specified factors, and allocates the next patient in an optimum way to help redress any imbalances that exist at that time. 

Since the publication of ICH E9 there has been considerable debate about the validity of dynamic allocation, even with the random element. There is a school of thought which has some sympathy within regulatory circles that supports the view that the properties of standard statistical methodologies, notably p-values and confidence intervals, are not strictly valid when such allocation schemes are used. As a result regulators are very cautious ... 

So if you are planning a trial then stick with stratification and avoid dynamic allocation. If you have an ongoing trial which is using dynamic allocation then continue, but be prepared at the statistical analysis stage to supplement the standard methods of calculating p-values with more complex methods which take account of the dynamic allocation scheme. These methods go under the name of randomisation tests. 

It was in this guideline where the use of dynamic allocation was discouraged (see... 

In dynamic SDR, the positions of members are not pre-assigned. Instead, the spaces in the key tree are dynamically allocated and reclaimed, adapting to the current set of active members. More specifically, the GCKS dynamically creates leaves when new member joins, or discards a subtree when all positions of the subtree are inactive. By doing this, the GCKS maintains active members in a dynamic key tree, rather than a large key tree constructed in advance. 

Jux A, Gleixner G, Boland W. Classification of terpenoids according to the methylerythritol phosphate or the mevalonate pathway with natural C/ C ratios dynamic allocation of resources in induced plants. Angew. Chem. Int. Ed. 2001 40 2091-2093. 

By dynamic allocation, in which treatment allocation is influenced by the current balance of allocated treatments... 

Millot P, Kamoun A. An implicit method for dynamic allocation between man and computer in supervision posts of automated processes. 3rd IFAC Congress on Analysis Design and Evaluation of Man Machine Systems. Oulu, Finhuid, June, 1988. 

The numerous short counting periods, the large number of vials coupled with the efficiency calibration data from the external standard count, the quenched standards, and the vials with mixtures of either scintillator-sample or scintillator-dead water make this a program of data organization and reduction. To eliminate the need to change the source progreun due to different numbers of observations from one sample run to another, the PL/1 feature of dynamic allocation of storage has been used. This allows the user to define the dimensions of the arrays for the input data. It is not uncommon for the arrays for the quenched standards, the dead water, and the sample data to have different dimensions. 

Talluri, K. van Ryzin, G./ THE THEORY AND PRACTICE OF REVENUE MANAGEMENT Kavadias, S. Loch, C.H.IPROJECT SELECTION UNDER UNCERTAINTY Dynamically Allocating Resources to Maximize Value... 

Designers should recognize that operators are not inherently flawed and subsequently should not simply remove or automate as many tasks as possible. This approach is likely to lead to mental underload and could leave operators with incoherent sets of tasks. The goal instead should be to design the system and procedures to exploit the skills of human operators. Physical workload should be kept to a minimum, whereas mental workload should be optimized. Ways to optimize mental workload include the use of adaptive interfaces (systems that can detect periods of elevated workload and then assist the operator accordingly) and dynamic allocation of function (systems that relieve the operator of task elements during high workload portions of the task). 

So far, the allocation of function between humans and machines could be assumed as being a one-shot effort allocation of function, once defined, remains static. Dynamic allocation of function is an alternative that makes it possible to adjust the division of labor between the human and the automation over time (Lee, 2006, p. 1581). This approach relies on two distinct antomation philosophies ... 

It is important to note that attractive, dynamic allocation of function is not a panacea. Improper design can quite often magnify the detrimental effects, of which there... 

In the case of dynamic allocation, there is an additional requirement to consider how these heuristics apply to the same functions but in different situations for example, a task could conceivably be repetitive and monotonous in one situation but encourage a feeling of usefulness in another. 

A set of functions to be performed by humans and machines in different situations or under varying criteria (in the case of dynamic allocation of function)... 

BS/EN/ISO 11064-1 2001 has a considerable amount of human factors best practice already embedded within it. It is, of course, possible to benefit still further, particularly in terms of the methods (and sequence of methods) that can be used to undertake functional analyses, task analyses, actual allocation of function, and the diagnosis of cognitive and affective criteria. The standard touches on the concept of dynamic allocation of function and this is explored further in this section. 

This type of analysis provides further insight for allocation of function decisions. Activities A and C might indicate situations where automation has to occur (and where it typically does occur). This is a useful check in terms of mandatory assignments. Activity B, on the other hand, shows a similar pattern for situation 1 (perhaps automation has to, and typically does, occur here) but not for situations 2 and 3. Activity could occur in these situations (but typically does not), yet the allocation of function decisions might be quite different in these cases. This, then, is one route to systematically considering dynamic allocation of function—that is, a form of automation that is situation dependent. 

Cognitive Woik Analysis also helps to facilitate dynamic allocation of function. This feature can be demonstrated with a contextual activity template derived from the same scenario. Figure 7.12 plots the anticipated modes of system operation specified in... 

In summary, the HTA tool is presented as a means by which a significant evaluation of basic requirements and preliminary allocations can be undertaken. The two CWA-based approaches are presented as means to extend that analysis beyond basic requirements and increase the quality of technical critique—in particular, positioning the analysis so dynamic allocation of function can be facilitated. 

Lastly, it is worthwhile noticing that the Hamiltonian given in Eq. [26] is conservative if the TB region is fixed, i.e., no dynamical allocation of the region is employed. However, a dynamical allocation of such a region may be extremely useful, for instance, in crack-propagation studies. A description of how this could be achieved is beyond the scope of this review, and we refer the interested reader to the original papers. 

Hsu, C.-L, Chao, C.-C. Shih, K.-Y. 2012. Dynamic allocation of check-in facilities and dynamic assignment of passengers at air terminals. Computers Industrial Engineering, 63, 410-417. 

Abstract In safety-critical embedded systems the stack typically is the only dynamically allocated memory area. However, the maximal stack nsage mnst be statically known at conflgnration time developers have to reserve enongh stack space for each task. Stack overflow errors are often hard to find bnt can cause the system to crash or behave erroneonsly. All cnrrent safety standards, e.g., ISO-26262, reqnire npper estimations of the storage space dne to its dynamic behavior the stack is an especially critical storage area. 

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