Statistics allocation

Maintainability, as a probability, can be mathematically defined between values zero and one, and the collected times to repair (TTR) can be statistically allocated to a specific distribution. 

Another way of interpreting absolute risk estimates is through the use of benchmarks or goals. Consider a company that operates 50 chemical process facilities. It is determined (through other, purely qualitative means) that Plant A has exhibited acceptable safety performance over the years. A QRA is performed on Plant A, and the absolute estimates are established as calibration points, or benchmarks, for the rest of the firm s facilities. Over the years, QRAs are performed on other facilities to aid in making decisions about safety maintenance and improvement. As these studies are completed, the results are carefully scrutinized against the benchmark facility. The frequency/consequence estimates are not the only results compared—the lists of major risk contributors, the statistical risk importance of safety systems, and other types of QRA results are also compared. As more and more facility results are accumulated, resources are allocated to any plant areas that are out of line with respect to the benchmark facility. 

This paper discusses the role that statistics can play In environmental sampling. The primary difference between an Investigation based on statistical considerations and one that Is not Is the degree of objectivity that can be Incorporated Into the evaluation of the quality and uncertainty of the study results. Statistical methods In the planning stage can also aid In optimizing allocation of resources. 

Degree of Precision Required. A statement of the required precision of the results from the sampling effort for each characteristic of Interest is needed to allocate sampling and testing resources efficiently. As previously discussed, the form of these statements will depend on the objective and type of characteristics. The users of the study results must make these determinations. Statistical methods to evaluate tradeoffs and alternatives may be useful in assisting the study administrators in this effort. 

Coomans D, Massart DL, Broeckaert I (1981) Potential methods in pattern recognition. A combination of ALLOC and statistical linear discriminant analysis. Anal Chim Acta 133 215... 

Burguete and Garcia26 in their article confirm the self-evident truth that the pharmaceutical sector allocates major budgets to the R D of products, occupying one of the leading positions in this respect among Spain s industries. In this study they use data provided by the National Institute of Statistics and the Central Balance Sheet Data Office of the Bank of Spain. 

Model of a supramolecular structure of polymolecular ensembles or clusters, determined by interaction and mutual arrangement of the forming molecules. At this level, the specific mechanisms of supramolecular chemistry, including molecular recognition, self-assembly, etc. [4] can be allocated. In most cases, it is possible to limit this area to objects with the sizes under 1 to 2 nm, since further increase in the sizes admits application of statistical concepts like phase and interphase surface. 

The geographical resolution is on the basis of NUTS (Nomenclature of Territorial Units for Statistics) areas, the regional classification of the European Union. For the German case study the NUTS3 classification (439 districts) has been used to analyse the demand allocation and fuelling station distribution as well as the regional infrastructure development. 

The main advantages of minimisation are that it achieves good balance on prognostic factors and thereby increases efficiency. However, it has been criticised, particularly deterministic minimisation, for not guaranteeing the imderlying randomness assumed by the statistical methods used to analyse the data. A second disadvantage is that because minimisation is a d)mamic process it uses information on subjects already entered to allocate to future patients. Since these patients may be in other centres the process is usually carried out by a centralised system using the internet, fax or telephone. 

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. 

The Diagnostic and Statistical Manual of Mental Disorders, 4th ed. (DSM-IV) criteria for ADHD include symptoms of inattention and hyperactivity or/impulsiv-ity patients can have either combined type, or predominantly inattentive (see below) or predominantly hy-peractive/impulsive types (American Psychiatric Association, 1994). Many of the symptoms of inattention relate to attentional abilities of the PFC—for example, difficulty sustaining attention, difficulty organizing, easily distracted, and forgetful. However, other symptoms described by DSM-FV could result from either PFC or posterior cortical attentional dysfunction— e.g., does not seem to listen, reluctance or difficulty engaging in tasks that require mental effort, poor attention to details. Thus, these symptoms could arise either due to poor attention regulation by the PFC or due to poor attentional allocation by the posterior cortices. Similarly, many of the symptoms of hyperactivity/... 

Although the ultimate source of much of particulate organic matter (POM) in the urban aerosol appears to be fossil fuel a specific knowledge of the amounts and classes of organic compounds contributed by various types of sources is lacking. Estimates of source contributions have been based on emission inventories which have been largely directed toward polycyclic aromatic hydrocarbons and/or benzo(a)pyrene. There has been very little work on the development of mathematical and statistical models for POM source identification and allocation (1). In view... 

Hermans, J., Habbema, J. D. Manual for the ALLOC-Discriminant Analysis Program, Dept. Medical Statistics, Univ. Leiden 1976... 

A bit allocation algorithm driven either by data statistics or by a perceptual... 

Although many examples of clinical investigation can be found throughout the history of medicine, the RCT emerged in the mid-20th century as the most powerful and scientifically sound way to establish the efficacy and safety of medicines. In 1948, Austin Bradford Hill used the statistical method of randomization with concealment of the allocation code to reduce biases related to selection and analysis of patients... 

Up to this time there has been no accepted nomenclature used to describe the activities and output of forensic laboratories. This absence of uniformity in basic record keeping has prevented the collection of data from more than a single Jurisdiction and the compilation of national statistics and assessments. There is little way of knowing if the allocation of federal funds into the forensic science field in the past several years has been worthwhile without such data. Management reporting models are needed so that they can be implemented and objective evaluations can be periodically performed to measure the performance and effectiveness of various laboratory configurations and operations. 

We should point out that the ability to fit equations of the form (5-18) or like (5-19), or of an even more complicated form, is predicated on having data from enough different mixtures to allow unambiguous identification of the parameters b. This requires proper data collection strategy. Much of the existing statistical research on the topic of mixture experiment design has to do with the question of wise allocation of experimental resources under the assumption that a particular type of equation is to be fit. 

---