STAT 270- Chapter 1 - People.stat.sfu.ca
STAT 270- Chapter 1 - People.stat.sfu.ca
STAT 270- Chapter 1 - People.stat.sfu.ca
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<strong>STAT</strong> <strong>270</strong>- <strong>Chapter</strong> 1<br />
May 6, 2012<br />
Shirin Golchi () <strong>STAT</strong><strong>270</strong> May 6, 2012 1 / 1
Why Statistics?<br />
Deterministic and Stochastic systems<br />
Deterministic systems: same set of inputs → same output<br />
e.g. physi<strong>ca</strong>l systems described by differential equations<br />
Stochastic systems: same set of inputs → different output<br />
e.g. tossing a coin<br />
Where does the randomness come from?<br />
Variation and uncertainty: The inputs of the system are never<br />
actually the same!<br />
Shirin Golchi () <strong>STAT</strong><strong>270</strong> May 6, 2012 2 / 1
Examples of <strong>stat</strong>isti<strong>ca</strong>l practice<br />
Sample surveys → labor force surveys<br />
Engineering → what needs to be known when building or expanding a<br />
bridge?<br />
Physics → particle physics (signal vs noise)<br />
etc.<br />
Shirin Golchi () <strong>STAT</strong><strong>270</strong> May 6, 2012 3 / 1
Statisti<strong>ca</strong>l analysis<br />
Experiment/Survey → Data → Statisti<strong>ca</strong>l analysis ↓<br />
Descriptive <strong>stat</strong>istics<br />
Inferential <strong>stat</strong>istics<br />
Usually start with descriptive <strong>stat</strong>istics to<br />
Data:<br />
Understand the data<br />
Summarize the data<br />
1 numeri<strong>ca</strong>l summaries<br />
2 graphi<strong>ca</strong>l summaries<br />
sample<br />
population<br />
Continue with inferential <strong>stat</strong>istics for sample data to understand the<br />
population.<br />
Shirin Golchi () <strong>STAT</strong><strong>270</strong> May 6, 2012 4 / 1
Probabiloty theory vs Statisti<strong>ca</strong>l Inference<br />
Probability theory: Uses information about the population to answer<br />
questions about the sample<br />
Inferential <strong>stat</strong>istics: Uses the sample to draw conclusions about the<br />
population<br />
Shirin Golchi () <strong>STAT</strong><strong>270</strong> May 6, 2012 5 / 1
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