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The degree to which each high-level task is broken down into lower-level tasks is dependent on the availability of HEPs for the successive individual branches. The HEPs may be derived from a range of sources such as the THERP database; simulation data; historical accident data, and expert judgment. PSFs should be incorporated into these HEP ...
The technique provides the user with useful suggestions as to how to reduce the occurrence of errors [4] It provides ready linkage between Ergonomics and Process Design, with reliability improvement measures being a direct conclusion which can be drawn from the assessment procedure.
Cluster data describes data where many observations per unit are observed. This could be observing many firms in many states or observing students in many classes. In such cases, the correlation structure is simplified, and one does usually make the assumption that data is correlated within a group/cluster, but independent between groups/clusters.
Sample sizes may be evaluated by the quality of the resulting estimates, as follows. It is usually determined on the basis of the cost, time or convenience of data collection and the need for sufficient statistical power. For example, if a proportion is being estimated, one may wish to have the 95% confidence interval be less than 0.06 units wide.
Contextual inquiry is a field data collection technique used to capture detailed information about how users of a product interact with the product in their normal work environment. This information is captured by both observations of user behavior and conversations with the user while she or he works.
Tukey defined data analysis in 1961 as: "Procedures for analyzing data, techniques for interpreting the results of such procedures, ways of planning the gathering of data to make its analysis easier, more precise or more accurate, and all the machinery and results of (mathematical) statistics which apply to analyzing data." [3]
Performing a probabilistic risk assessment starts with a set of initiating events that change the state or configuration of the system. [3] An initiating event is an event that starts a reaction, such as the way a spark (initiating event) can start a fire that could lead to other events (intermediate events) such as a tree burning down, and then finally an outcome, for example, the burnt tree ...
where Pc is the cumulative probability and N is the number of data. It is seen that the standard deviation Sd reduces at an increasing number of observations N. The determination of the confidence interval of Pc makes use of Student's t-test (t). The value of t depends on the number of data and the confidence level of the estimate of the ...