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| public:e-217-prog-2010-1:thorisson-simulation-1 [2010/03/24 16:14] – thorisson | public:e-217-prog-2010-1:thorisson-simulation-1 [2024/04/29 13:33] (current) – external edit 127.0.0.1 |
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| | Simulation | A model of a process that can transform an initial state to a future state. S -> S' | | | Simulation | A model of a process that can transform an initial state to a future state. S -> S' | |
| | Scientific Method | In Western science, the usage of a set of principles that facilitate the production of reliable knowledge | | | Scientific Method | In Western science, the usage of a set of principles that facilitate the production of reliable knowledge | |
| | Theory (isl. kenning) | Explain the connections between things in the world. \\ “A set of statements or principles devised to explain a group of facts or phenomena, especially one that has been repeatedly tested or is widely accepted and can be used to make predictions about natural phenomena.” [[http://dictionary.reference.com/search?q=theory|REF]] \\ A theory is a relatively big explanation, covering several phenomena, often through a single principle, or a set of simple principles. | | | Theory (isl. kenning) | Explain the connections between things in the world. \\ “A set of statements or principles devised to explain a group of facts or phenomena, especially one that has been repeatedly tested or is widely accepted and can be used to make predictions about natural phenomena.” [[http://dictionary.reference.com/search?q=theory|REF]] \\ A theory is a relatively big explanation, covering several phenomena, often through a single principle, or a set of simple principles. | |
| | Hypothesis (isl. tilgáta) | Is a prediction about the relationship between a limited set of phenomena, as explained by a particular theory | | | Hypothesis (isl. tilgáta) | Is a prediction about the relationship between a limited set of phenomena, as explained by a particular theory | |
| | Experimental design | “A planned interference in the natural order of events" | | | Experimental design | “A planned interference in the natural order of events" | |
| | Sample: Subject selection from a “population” A representative subset, drawn from a population, of the phenomenon we are studying. | Typically you can't study all the individuals of a particular subject pool, so in your experiment you use a sample and hope that the results generalize to the rest of the subjects. \\ Examples: \\ a. Siggi, Maggi and Biggi representing human males. \\ b. 10 lakes representing all freshwater on the Earth's surface. \\ c. rust on bottom of doors representing the overall state of an automobile. \\ A sample should be randomly chosen to (1) minimize spurious correlations and thus (2) maximize the generalizability of the results of measuring only a small subset of the phenomenon. | | | Dependent variable(s) | These are "the things we want to measure", e.g. the speedup seen with the new word processor. \\ Values are measured during and/or after the experiment. | |
| | | Independent variables | These are factors that need to be controlled for the results to be more intelligible. Example: If we want to study the efficiency speedup seen by a new multi-cultural word processor we would want to have all or some of the cultures represented when we do the study. \\ We select their **values** - the values are known when we start an experiment. \\ Any independent variable must have at least 2 levels (values), so its effect can be evaluated. | |
| | | Sample: Subject selection from a “population” A representative subset, drawn from a population, of the phenomenon we are studying. | Typically you can't study all the individuals of a particular subject pool, so in your experiment you use a sample and hope that the results generalize to the rest of the subjects. \\ Examples: \\ a. Siggi, Maggi and Biggi representing human males. \\ b. 10 lakes representing all freshwater on the Earth's surface. \\ c. rust on bottom of doors representing the overall state of an automobile. \\ A sample should be randomly chosen to (1) minimize spurious correlations and thus (2) maximize the generalizability of the results of measuring only a small subset of the phenomenon. | |
| | Randomness | It is hypothesized in quantum physics that the universe may possibly be built on a truly random foundation, which means that some things are by their very nature unpredictable. Randomness in the aggregate, however, does seem to follow some predictable laws (c.f. the concept of "laws of probability"). | | | Randomness | It is hypothesized in quantum physics that the universe may possibly be built on a truly random foundation, which means that some things are by their very nature unpredictable. Randomness in the aggregate, however, does seem to follow some predictable laws (c.f. the concept of "laws of probability"). | |
| | Sample Distribution | If you sample data many times it may not always give the same result. \\ Example: If you measure the temperature repeatedly over a full day, the values you get will not be identical, they will be distributed. | | | Sample Distribution | If you sample data many times it may not always give the same result. \\ Example: If you measure the temperature repeatedly over a full day, the values you get will not be identical, they will be distributed. | |
| | Normal distribution | The Bell Curve. Also called Gaussian Distribution. \\ {{:public:e-217-prog-2010-1:bellcurve1.jpg|Bell Curve}}\\ [[public:e-217-prog-2010-1:thorisson-simulation-1:NaturalBellCurve|See picture]] | | | Normal distribution | The Bell Curve. Also called Gaussian Distribution. \\ {{:public:e-217-prog-2010-1:bellcurve1.jpg|Bell Curve}}\\ [[public:e-217-prog-2010-1:thorisson-simulation-1:NaturalBellCurve|See picture]] | |
| | Data | Typically “raw numbers” – only contain low-level semantics | | | Data | Typically “raw numbers” – only contain low-level semantics | |
| | Information | Processed and prepared data | | | Information | Processed and prepared data | |
| | Statistics | Mathematical methods for dealing with uncertainty | | | Statistics | Mathematical methods for dealing with uncertainty | |
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| ====Where Simulation Fits In Science==== | ====Where Simulation Fits In Science==== |
| | Challenges | a. Grounding Simulations \\ b. Detail \\ c. Abstraction | | | Challenges | a. Grounding Simulations \\ b. Detail \\ c. Abstraction | |
| | Grounding | The connection between a simulation (model) and reality | | | Grounding | The connection between a simulation (model) and reality | |
| | Complexity | How complex should we make a model/simulation? | | | Complexity | How complex should we make a model/simulation? More complexity ≠ more explanatory power | |
| | Abstraction | How abstract can we make things? \\ What is the difference between simulating market behavior by modeling every individual consumer, versus modeling the market behavior grossly as "percent of those who buy"? | | | Abstraction | How abstract can we make things? \\ What is the difference between simulating market behavior by modeling every individual consumer, versus modeling the market behavior grossly as "percent of those who buy"? | |
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| | Exogeneous variables | Independent variable that affects a model without being affected by it, and whose qualitative characteristics and method of generation are not specified by the model builder. An exogenous variable is used for setting arbitrary external conditions, and not in achieving a more realistic model behavior. For example, the level of government expenditure is exogenous to the theory of income determination. [[http://www.businessdictionary.com/definition/exogenous-variable.html|REF]] | | | Exogeneous variables | Independent variable that affects a model without being affected by it, and whose qualitative characteristics and method of generation are not specified by the model builder. An exogenous variable is used for setting arbitrary external conditions, and not in achieving a more realistic model behavior. For example, the level of government expenditure is exogenous to the theory of income determination. [[http://www.businessdictionary.com/definition/exogenous-variable.html|REF]] | |
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| | [[http://cadia.ru.is/wiki/public:e-217-prog-2010-1:thorisson-simulation-2|Thórisson Lecture 2 ->]] |
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