2942457
Description
Flashcards by Samuel Metcalfe, updated more than 1 year ago
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Created by Samuel Metcalfe
over 9 years ago
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| Question | Answer |
| Aleatoric Uncertainty | Statistical uncertainy, from natural randomness e.g Earthquakes, Human Behaivour etc. |
| Epistemic Uncertainty | Systematic uncertainty that comes from inaccuracies in understandings and models. |
| The three options of action with uncertainties | - Ignore - Allow for using intuition (ie Engineering Judgement) - Scientific approach by using probabilistic and statistical analysis |
| Null Hypothesis | A general statement or default position that there is no relationship between two measured phenomena |
| Type I Error | Null Hypothesis is correct but is rejected - false positive |
| Type II Error | Null Hypothesis is false but is not rejected - false negative |
| How to fix type I and type II errors respectively | Type I - Increase your level of confidence (more precise) Type 2 - Descriptive testing (more detailed) ##clarify later## |
| Risk analysis | A technique used to identify and assess factors that may jeopardize the success of a project or achieving a goal. |
| Risk Management | Identifying the probability and consequence of making the wrong decisions |
| State of Nature (SON) | The true value of an uncertain variable. It can never be determined with absolute confidence. |
| How to get and refine a SON | You can estimate the SON through prior knowledge, and obtain additional information to refine it by doing experiments |
| Statistical Decision Theory | Identifies the optimal decision when given a probability distribution for a state of nature |
| Preposterior Analysis | When there are several possible tests identifying which one needs to be done. Tests should only be done id expected value of information is greater than obtaining cost. |
| Stages of Posterior Analysis | 2 Stages in Decision Tree - Action and State |
| Stages of Preposterior analysis | 4 Stages- Test (e), result (z), action(a), state (theta) |
| Allais' Paradox | Actual observed choices are inconsistent with predictions from expected utility theory |
| Rational Decision-making approach | Making decisions purely based on probability and consequence of each possible outcome |
| Utility | Essentially the benefits something gives |
| Robust numerical measure of preference requirements | - Has a scale ordering expected values Reflects decision makers subjective preferences |
| Standard Gamble | Allows subjectivity, whilst preserving order of expected values. It is based on a decision tree, one leading to a certain outcome, the other a gamble. |
| Three different types of decision making criteria (alternatives to rational approach) | - Criteria of Pessimism For each action find minimum utility. Choose action with largest - Criteria of Optimism For each action find maximum utility. Choose action with largest - Criterion of regret Make table of regret, choose action with smallest maximum regrt |
| Reliability | Probability that component (or system) will function properly |
| Assumptions made in reliability engineering | - All components are independent - No partial failures - Known reliabilities per component |
| Types of systems | Series - System survives if all components survive Parallel - System survives if not all components fail |
| Birnbaum Reliability | Improve the link with highest Reliability Importance In series - Improve the weaker link In parallel - Improve the stronger link |
| Henly and Kumamoto | Improve link with highest Critical Importance In series - Either or In parallel - Improve weaker link |
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