Planning errors

Some aspects of cognitive errors, that is, planning errors, can be addressed. 

If the procedures were not regularly updated or were otherwise incorrect, or if training was inadequate, PI errors could occur. P2 errors would often arise as a result of misdiagnosing a situation, or if the entry conditions for executing a sequence of operations were ambiguous or difficult to assess and therefore the wrong procedure was selected. It is important to note that if a planning error occurs, then this implies that a detailed analysis needs to be conducted of the alternative course of action that could arise. 

Once an attractive product has been identified, the time factor becomes extremely important, risk and cost are no longer the only relevant criteria. From now on speed and efficiency are of paramount importance. A minor planning error which results in a delay of a task on the critical path for only one month can delay the entire project by one month. Almost inevitably it also adds 1/12 of the annual budget to the development cost. Thus, in a project with an average annual budget of 2.5 million, a delay like this can cost more than 200,000. Apart from these direct cost, later access to the market can cause much higher losses. 

One of the difficulties in eliminating planning errors or mistakes is that such errors are often only visible in hindsight. With the information available at the time, the decisions may seem reasonable. In addition, planning errors are a necessary side effect of human problem-solving ability. Completely eliminating mistakes or planning errors (if possible) would also eliminate the need for humans as controllers. 

Planning errors arise from the basic human cognitive ability to solve problems. Human error in one situation is human ingenuity in another. Human problem solving rests on several unique human capabilities, one of which is the ability to create hypotheses and to test them and thus create new solutions to problems not previously considered. These hypotheses, however, may be wrong. Rasmussen has suggested that human error is often simply unsuccessful experiments in an unkind environment, where an unkind environment is defined as one in which it is not possible for the human to correct the effects of inappropriate variations in performance... 

Planning errors cause wrong designs and construction flaws and lead to wrong or insufficient instructions in the operating manual. Planning errors stem, for example, from mutual dependencies which have not been identified or sufficiently accounted for as the dependence of human error probabilities on environmental influences or impairment of components due to changes in environmental conditions caused by an accident. 

However, the problem with hashish and marijuana as a medication is their route of apphcation and their standardisation. Resorption kinetics and bioavail-abftity are highly dependent on the administration form. In addition, the content of active ingredients in cannabis fluctuates considerably, what makes it hard to compare data from different chnical studies, apart from any potential planning errors that may also have occiured. Microbial pollutants, which lead to allergies and breathing illnesses, pose another problem. AH this favours the chemical total synthesis of the pure active material. Thereby, a targeted co-administration of several cannabinoids may become feasible in the future. 

Any errors that remain are of course my own responsibility. If you do find any, I would like to know 1 will also be pleased to receive any constructive suggestions, comments or criticisms. We plan to set up a web site that will provide access to various material from the book (such as electronic versions of the colour images) together with email contacts. This cem be accessed via www.booksites.net. 

In test planning, the number to be placed on test n and the number of failures rmust be deterrnined. The operating characteristic curves in Reference 18 can be used to specify the test, and to control the errors. 

Conduct the trials as planned. Results should be carefully recorded in a table or machine along with any observations which may be regarded as potential errors... 

Now you can reconsider the material balance equations by adding those additional factors identified in the previous step. If necessary, estimates of unaccountable losses will have to be calculated. Note that, in the case of a relatively simple manufacturing plant, preparation of a preliminary material-balance system and its refinement (Steps 14 and 15) can usefully be combined. For more-complex P2 assessments, however, two separate steps are likely to be more appropriate. An important rule to remember is that the inputs should ideally equal the outputs - but in practice this will rarely be the case. Some judgment will be required to determine what level of accuracy is acceptable, and we should have an idea as to what the unlikely sources of errors are (e.g., evaporative losses from outside holding ponds may be a materials loss we cannot accurately account for). In the case of high concentrations of hazardous wastes, accurate measurements are needed to develop cost-effective waste-reduction options. It is possible that the material balance for a number of unit operations will need to be repeated. Again, continue to review, refine, and, where necessary, expand your database. The compilation of accurate and comprehensive data is essential for a successful P2 audit and subsequent waste-reduction action plan. Remember - you can t reduce what you don t know is therel... 

Contact temperature measurement is based on a sensor or a probe, which is in direct contact with the fluid or material. A basic factor to understand is that in using the contact measurement principle, the result of measurement is the temperature of the measurement sensor itself. In unfavorable situations, the sensor temperature is not necessarily close to the fluid or material temperature, which is the point of interest. The reason for this is that the sensor usually has a heat transfer connection with other surrounding temperatures by radiation, conduction, or convection, or a combination of these. As a consequence, heat flow to or from the sensor will influence the sensor temperature. The sensor temperature will stabilize to a level different from the measured medium temperature. The expressions radiation error and conduction error relate to the mode of heat transfer involved. Careful planning of the measurements will assist in avoiding these errors. 

Verification of some characteristics may only be possible by calculation rather than by test, inspection, or demonstration. In such cases the design calculations should be checked either by being repeated by someone else or by performing the calculations by an alternative method. When this form of verification is used the margins of error permitted should be specified in the verification plan. 

Importance also applies to what may appear minor decisions in the planning or design phase. If such decisions are incorrect they could result in major problems downstream. If not detected, getting the decimal place wrong or the units of measure wrong can have severe consequences. Audits should verify that the appropriate controls are in place to detect such errors before it is too late. 

The book begins with a discussion of the theories of error causation and then goes on to describe the various ways in which data can be collected, analyzed, and used to reduce the potential for error. Case studies are used to teach the methodology of error reduction in specific industry operations. Finally, the book concludes with a plan for a plant error reduction program and a discussion of how human factors principles impact on the process safety management system. 

Chapter 8, A Systematic Approach to the Management of Human Error, explains how the manager and safety professional can use human factors principles in the management of process safety. This chapter also provides a practical plan for a plant human error reduction program that will improve productivity and quality as well. 

The dotted lines in the diagram indicate the various feedback paths that exist to enable the individual to identify if a particular stage of the processing chain was executed correctly. Thus, if the operating team had planned a strategy to handle a complex plant problem, they would eventually obtain feedback with regard to whether or not the plan was successful. Similar feedback loops exist at the rule and skill-based levels, and indicate opportunities for error correction. The application of the stepladder model to a process industry example is given in Appendix 2A at the end of this chapter. 

Preconditioned plan analysis Tlris addresses errors in the planning of the task or ensuring that the correct preconditions apply. 

Embedded plan analysis Tlris considers errors arising from the plan specified in the HTA (e.g., ignoring the condition in the plan which specifies how the steps should be executed). 

---