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StatisticsStatistics is the science and practice of developing human knowledge through the use of empirical data. It is based soundly on statistical theory which is a branch of applied mathematics. Within statistical theory, randomness and uncertainty are modelled by probability theory. Statistical practice includes the planning, summarizing, and interpreting of uncertain observations. Because the aim of statistics is to produce the "best" information from available data, some authors make statistics a branch of decision theory.
Origin
The word statistics comes from the modern Latin phrase statisticum collegium (lecture about state affairs), from which came the Italian word statista, which means "statesman" or "politician" (compare to status) and the German Statistik, originally designating the analysis of data about the state. It acquired the meaning of the collection and classification of data generally in the early nineteenth century. The collection of data about states and localities continues, largely through national and international statistical services; in particular, censuses provide regular information about the population.
Statistical methods
We describe our knowledge (and ignorance) mathematically and attempt to learn more from whatever we can observe. This requires us to
- plan our observations to control their variability (experiment design),
- summarize a collection of observations to feature their commonality by suppressing details (descriptive statistics), and
- reach consensus about what the observations tell us about the world we observe (statistical inference).
In some forms of descriptive statistics, notably data mining, the second and third of these steps become so prominent that the first step (planning) appears to become less important. In these disciplines, data often are collected outside the control of the person doing the analysis, and the result of the analysis may be more an operational model than a consensus report about the world.
Probability
The probability of an event is often defined as a number between one and zero. In reality however there is virtually nothing that has a probability of 1 or 0. You could say that the sun will certainly rise in the morning, but what if an extremely unlikely event destroys the sun? What if there is a nuclear war and the sky is covered in ash and smoke?
We often round the probability of such things up or down because they are so likely or unlikely to occur, that it's easier to recognise them as a probability of one or zero.
However, this can often lead to misunderstandings and dangerous behaviour, because people are unable to distinguish between, e.g., a probability of 10-4 and a probability of 10-9, despite the very practical difference between them. If you expect to cross the road about 105 or 106 times in your life, then reducing your risk of being run over per road crossing to 10-9 will make you safe for your whole life, while a risk per road crossing of 10-4 will make it very likely that you will have an accident, despite the intuitive feeling that 0.01% is a very small risk.
Use of prior probabilities of 0 (or 1) causes problems in Bayesian statistics, since the posterior distribution is then forced to be 0 (or 1) as well. In other words, the data is not taken into account at all! As Lindley puts it, if a coherent Bayesian attaches a prior probability of zero to the hypothesis that the Moon is made of green cheese, then even whole armies of astronauts coming back bearing green cheese cannot convince him. Lindley advocates never using prior probabilities of 0 or 1. He calls it Cromwell's Rule, from a letter Oliver Cromwell wrote to the synod of the Church of Scotland on August 5th, 1650 in which he said "I beseech you, in the bowels of Christ, consider it possible that you are mistaken."
Specialized disciplines
Some sciences use applied statistics so extensively that they have specialized terminology. These disciplines include:
Statistics form a key basis tool in business and manufacturing as well. It is used to understand measurement systems variability, control processes (as in statistical process control or SPC), for summarizing data, and to make data-driven decisions. In these roles it is a key tool, and perhaps the only reliable tool.
See also
Lindley, D. Making Decisions. John Wiley. Second Edition 1985.
External links
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China Statistical Information Network
Chinese National Bureau of Statistics. Provides general and economic data such as a monthly index of retail and consumer prices at city level for 2000. Also contains census information from 1998 and 1999.
http://www.stats.gov.cn/english/index.htm
Philippine National Statistical Coordination Board
Philippines' policy making and coordinating body on statistical matters.
http://www.nscb.gov.ph/
Singapore Department of Statistics
Provides a range of detailed economic, financial and socio-economic indicators.
http://www.singstat.gov.sg/
Pakistan - Statistics Division
Includes the Federal Bureau of Statistics, the Population Census Organization and the Agricultural Census Organization.
http://www.statpak.gov.pk/
Asia Pacific Economic Co-operation Forum
Economic data provided by APEC Forum.
http://www.apecsec.org.sg/
Hong Kong - Census and Statistics Department
Includes short articles on the basics of official statistics.
http://www.info.gov.hk/censtatd/
Indonesia - Badan Pusat Statistik
Statistics Indonesia is a non-departmental government institution directly responsible to the President.
http://www.bps.go.id/
South Korea - National Statistical Office
Major Korean statistics.
http://www.nso.go.kr/eng/
Taiwan - Directorate-General of Budget, Accounting and Statistics
The DGBAS is in charge of national budgeting, accounting and statistical affairs.
http://www.dgbasey.gov.tw/english/dgbas_e0.htm
India Statistics
Comprehensive site providing socio-economic research data for India.
http://www.indiastat.com/
Malaysia - Department of Statistics
Detailed information on GDP, consumer and producer prices, trade and industry.
http://www.statistics.gov.my/
Japanese Statistics Bureau and Statistics Centre
Includes economic and general information such as retail and consumer prices and family income and expenditure data.
http://www.stat.go.jp/english/index.htm
Thailand - National Statistical Office
Statistical site providing economic, agriculture, industry and socio-economic data.
http://www.nso.go.th/
Korea - National Statistical Office
Regularly updated with Korean economic information.
http://www.nso.go.kr/
Maldives - Ministry of Planning and National Development
The Statistics Section of which has histories of a variety of basic economic variables.
http://www.planning.gov.mv/
Armenia - National Statistical Service of the Republic of Armenia
Includes basic economic details about Armenia. Very slow site.
http://www.armstat.am/
Sri Lanka - Department of Census Statistics
Provides basic economic and socio-economic data, although it is dated (1995).
http://www.statistics.gov.lk/
Kazakhstan - Agency of Statistics of the Republic of Kazakhstan
Provides information about the statistical series available to subscribers.
http://www.stat.kz/en/releases/
Macau - Statistics and Census Service
A department of the Public Administration of Macau, in charge of the orientation, co-ordination, execution and control of the statistical activities in Macao.
http://www.dsec.gov.mo/
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