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Introducing Statistics: A Graphic Guide



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Author: Eileen Magnello

Publisher: Icon Books

Genres:

Publish Date: October 15, 2005

ISBN-10: 1848310560

Pages: 176

File Type: EPub

Language: English

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Book Preface

Drowning by Numbers

We are drowning in statistics. And they are not just numbers. For the media, statistics are routinely “damning”, “horrifying”, “deadly”, “troublesome” – or, on occasion, “encouraging”. The press constantly suggest that statistical information about crime, disease, poverty and transport delays is not only the source of the problem, but that it represents real entities or real people instead of one point on a graph.

Averages or Variation?

Much of the shock-horror statistical information used by the media is based on statistical averages. Despite the often misleading preoccupation with averages, the most important statistical concept neglected by journalists and news reporters is variation. This concept is essential to modern mathematical statistics and plays a pivotal role in biological, medical, educational and industrial statistics.

Why Study Statistics?

Statistics are used by scientists, economists, government officials, industry and manufacturers. Statistical decisions are made constantly and affect our daily lives – from the medicine we take, the treatments we receive, the aptitude and psychometric tests employers give routinely, the cars we drive, the clothes we wear (wool manufacturers use statistical tests to determine the thread weave for our comfort) to the food we eat and even the beer we drink.

What are Statistics?

Yet for all their ubiquity, we don’t really know what to make of statistics. As one columnist put it, “cigarettes are the biggest single cause of statistics”. People express a wish to avoid bad things by saying, “I don’t want to be another statistic”. Do statisticians really think that all of humanity is reducible to a few numbers?

Although some people think that statistical results are irrefutable, others believe that all statistical information is deceptive

What Does Statistics Mean?

The word “statistics” is derived from the Latin status, which led to the Italian word statista, first used in the 16th century, referring to a statist or statesman – someone concerned with matters of the state. The Germans used Statistik around 1750, the French introduced statistique in 1785 and the Dutch adopted statistiek in 1807.

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Early statistics was a quantitative system for describing matters of state – a form of “political arithmetic”.

The system was first used in 17th-century England by the London merchant John Graunt (1620–74) and the Irish natural philosopher William Petty (1623–87).

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In the 18th century, many statists were jurists; their background was often in public law (the branch of law concerned with the state itself).

It was the Scottish landowner and first president of the Board of Agriculture, Sir John Sinclair (1754–1834), who introduced the word “statistics” into the English language in 1798 in his Statistical Account of Scotland.

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I wanted to measure the “quantum of happiness” of the Scots. The What?

Sinclair used statistics for social phenomena rather than for political matters. This led eventually to the development of vital statistics in the mid-19th century.

Vital Statistics vs. Mathematical Statistics

Not all statistics are the same. There are two types: vital statistics and mathematical statistics.

Vital statistics is what most people understand by statistics. It is used as a plural noun and refers to an aggregate set of data.

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It refers to the description and enumeration used in census counts or in the tabulation of official statistics such as marriage, divorce and crime statistics. We also have insurance statistics and even cricket and baseball statistics.

This process is primarily concerned with average values, and uses life tables, percentages, proportions and ratios: probability is most commonly used for actuarial (i.e. life-insurance) purposes. It was not until the 20th century that the singular form “statistic”, signifying an individual fact, came into use.

Mathematical statistics is used as a singular noun, and it arose out of the mathematical theory of probability in the late 18th century from the work of such continental mathematicians as Jacob Bernoulli, Abraham DeMoivre, Pierre-Simon Laplace and Carl Friedrich Gauss.

In the late 19th century, mathematical statistics began to take shape as a fully-fledged academic discipline in the work of Francis Ysidro Edgeworth (1845–1926), John Venn (1834–1923), Francis Galton (1822–1911), W.F.R. Weldon (1860–1906) and Karl Pearson (1857–1936).

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We three began to apply Charles Darwin’s ideas to the measurement of biological variation, which required a new statistical methodology.

Mathematical statistics encompasses a scientific discipline that analyses variation, and is often underpinned by matrix algebra. It deals with the collection, classification, description and interpretation of data from social surveys, scientific experiments and clinical trials. Probability is used for statistical tests of significance.

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Mathematical statistics is analytical and can be used to make statistical predictions or inferences about the population. Furthermore, it capitalizes on all the individual differences in a group by examining the spread of this statistical variation through such methods as the range and standard deviation, which we’ll look at later. Vital statistics is concerned with averages, whereas mathematical statistics deals with variation.

Used in this sense, statistics is a technical discipline, and while it is mathematical, it is essential to understand the statistical concepts underlying the mathematical procedures.

Contents

Cover

Title Page

Copyright

Drowning by Numbers

Averages or Variation?

Why Study Statistics?

What are Statistics?

What Does Statistics Mean?

Vital Statistics vs. Mathematical Statistics

The Philosophy of Statistics

Darwin and Statistical Populations

Victorian Values

Where Did it All Begin?

Parish Registers

The London Bills of Mortality

Halley’s Mortality Tables

Malthusian Populations

Demography – the Science of Populations

The Statistical Society of London

Edwin Chadwick and Sanitary Reforms

William Farr and Vital Statistics

Florence Nightingale: the Passionate Statistician

The Statistics of the Crimean War

Mortality Statistics in the Crimea

Polar Area Graphs

Probability

Variables

Games of Chance

De Moivre and Gambling in Soho

The Mathematical Theory of Probability

Relative Frequency

The Bayesian Approach

Probability Distributions

The Poisson Distribution

The Normal Distribution

Astronomical Observations

The Central Limit Theorem

The Gaussian Curve and the Principle of Least Squares

What’s Normal?

The Naming of the Normal

So What is the Normal Distribution?

Quetelismus

Galton’s Pantograph

How to Summarise the Data?

Quetelet and the Arithmetical Mean

The Mean

The Median

How to Locate or Calculate the Median

Does it Matter Which Statistical Average is Used?

Misleading With Statistics

Data Management Procedures

Standardized Frequency Distributions

Samples vs. Populations

The Histogram

Frequency Distributions

The Method of Moments

Natural Selection: the Changing Shapes of Darwinian Distributions

The Peppered Moth

The Pearsonian Family of Curves

The Interquartile Range

The Standard Deviation

Coefficient of Variation

Comparing Variation of Variables

Practical Applications

Pearson’s Scales of Measurement

Nominal and Ordinal Variables

Ratio and Interval

Early Uses of Correlation

Causation and Spurious Correlation

Path Analysis and Causation

Scatter Diagrams

Weldon and Negative Correlation

Curvilinear Relationships

Galton and Biological Regression

Regression to the Mean

Galton’s Two Regression Lines

George Udny Yule and the Method of Least Squares

Correlation vs. Regression

Galton’s Dilemma

Pearson’s Product-Moment Correlation

Simple Correlation and Multiple Correlation

Statistical Control

Discrete 2 × 2 Relationships

Biserial Correlations

Egon Pearson and Polychoric Correlations

Factor Analysis

Maurice Kendall’s Tau Coefficient

Correlation vs. Association

Curve-Fitting for Asymmetrical Distributions

Interpreting Results with Degrees of Freedom

The Chi-Square Probability Table

A Statistical Test for the Guinness Brewery

Quantifying Brewery Material

Agricultural Variation

Small Samples vs. Large Samples

Testing Statistical Differences Between Two Means

Statistical Results for Guinness

Student’s t-test

A New Statistical Era: Rothamsted’s Broadbalk Agricultural Data

Fisher’s Statistical Analysis of Variance

The Analysis of Agricultural Variation

The Analysis of Variance and Small Samples

Inferential Statistics

The Sampling Distribution

Conclusion

Bibliography

About the Author

Index


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