In economics, the Gini coefficient, sometimes called the Gini index or Gini ratio, is a measure of statistical dispersion intended to represent the income or wealth distribution of a nation's residents, is the most used measurement of inequality. It was developed by the Italian statistician and sociologist Corrado Gini and published in his 1912 paper Variability and Mutability; the Gini coefficient measures the inequality among values of a frequency distribution. A Gini coefficient of zero expresses perfect equality. A Gini coefficient of one expresses maximal inequality among values. For larger groups, values close to one are unlikely in practice. Given the normalization of both the cumulative population and the cumulative share of income used to calculate the Gini coefficient, the measure is not overly sensitive to the specifics of the income distribution, but rather only on how incomes vary relative to the other members of a population; the exception to this is in the redistribution of income resulting in a minimum income for all people.

When the population is sorted, if their income distribution were to approximate a well-known function some representative values could be calculated. The Gini coefficient was proposed by Gini as a measure of inequality of wealth. For OECD countries, in the late 20th century, considering the effect of taxes and transfer payments, the income Gini coefficient ranged between 0.24 and 0.49, with Slovenia being the lowest and Mexico the highest. African countries had the highest pre-tax Gini coefficients in 2008–2009, with South Africa the world's highest, variously estimated to be 0.63 to 0.7, although this figure drops to 0.52 after social assistance is taken into account, drops again to 0.47 after taxation. The global income Gini coefficient in 2005 has been estimated to be between 0.61 and 0.68 by various sources. There are some issues in interpreting a Gini coefficient; the same value may result from many different distribution curves. The demographic structure should be taken into account. Countries with an aging population, or with a baby boom, experience an increasing pre-tax Gini coefficient if real income distribution for working adults remains constant.

Scholars have devised over a dozen variants of the Gini coefficient. The Gini coefficient is a single number aimed at measuring the degree of inequality in a distribution, it is most used in economics to measure how far a country's wealth or income distribution deviates from a equal distribution. The Gini coefficient is defined mathematically based on the Lorenz curve, which plots the proportion of the total income of the population, cumulatively earned by the bottom x of the population; the line at 45 degrees thus represents perfect equality of incomes. The Gini coefficient can be thought of as the ratio of the area that lies between the line of equality and the Lorenz curve over the total area under the line of equality, it is equal to 2A and to 1 − 2B due to the fact that A + B = 0.5. If all people have non-negative income, the Gini coefficient can theoretically range from 0 to 1. In practice, both extreme values are not quite reached. If negative values are possible the Gini coefficient could theoretically be more than 1.

The mean is assumed positive, which rules out a Gini coefficient less than zero. An alternative approach is to define the Gini coefficient as half of the relative mean absolute difference, mathematically equivalent to the Lorenz curve definition; the mean absolute difference is the average absolute difference of all pairs of items of the population, the relative mean absolute difference is the mean absolute difference divided by the average, x ¯, to normalize for scale. If xi is the wealth or income of person i, there are n persons the Gini coefficient G is given by: G = ∑ i = 1 n ∑ j = 1 n | x i − x j | 2 ∑ i = 1 n ∑ j = 1 n x j = ∑ i = 1 n ∑ j = 1 n | x i − x j | 2 n ∑ i = 1 n x i = ∑

Bitcoin is a digital asset designed by its inventor, Satoshi Nakamoto, to work as a currency. Bitcoin is a digital asset designed by Satoshi Nakamoto, to work as a currency, it is referred to with terms like: digital currency, digital cash, virtual currency, electronic currency, digital gold, or cryptocurrency. The question whether bitcoin is a currency or not is disputed. Bitcoins have three useful qualities in a currency, according to The Economist in January 2015: they are "hard to earn, limited in supply and easy to verify". Economists define money as a store of value, a medium of exchange and a unit of account, agree that bitcoin has some way to go to meet all these criteria, it does best as a medium of exchange: As of March 2014, the bitcoin market suffered from volatility, limiting the ability of bitcoin to act as a stable store of value, retailers accepting bitcoin use other currencies as their principal unit of account. Classification of bitcoin by the United States government is to date unclear with multiple conflicting rulings.

In 2013 Judge Amos L. Mazzant III of the United States District Court for the Eastern District of Texas stated that "Bitcoin is a currency or form of money". In July 2016, Judge Teresa Mary Pooler of Eleventh Judicial Circuit Court of Florida cleared Michell Espinoza in State of Florida v. Espinoza in money-laundering charges he faced involving his use of bitcoin. Judge Pooler stated "Bitcoin may have some attributes in common with what we refer to as money, but differ in many important aspects, they are not tangible wealth and cannot be hidden under a mattress like cash and gold bars." In September 2016, a ruling by Judge Alison J. Nathan of United States District Court for the Southern District of New York contradicted the Florida Espinoza ruling stating "Bitcoins are funds within the plain meaning of that term.— Bitcoins can be accepted as a payment for goods and services or bought directly from an exchange with a bank account. They therefore function as pecuniary resources and are used as a medium of exchange and a means of payment."

The U. S. Treasury categorizes bitcoin as a decentralized virtual currency; the Commodity Futures Trading Commission classifies bitcoin as a commodity, the Internal Revenue Service classifies it as an asset. The South African Revenue Service, the legislation of Canada, the Ministry of Finance of the Czech Republic and several others classify bitcoin as an intangible asset; the Bundesbank says that bitcoin is not digital money. It recommends using the term "crypto token."The People's Bank of China has stated that bitcoin "is fundamentally not a currency but an investment target". Journalists and academics debate what to call bitcoin; some media outlets do make a distinction between "real" money and bitcoins, while others call bitcoin real money. The Wall Street Journal declared it a commodity in December 2013. A Forbes journalist referred to it as digital collectible. Two University of Amsterdam computer scientists proposed the term "money-like informational commodity". In a 2016 Forbes article, bitcoin was characterized as a member of a new asset class.

In addition to the above, bitcoin is characterized as a payment system.:1 According to research produced by Cambridge University in 2017, there are between 2.9 million and 5.8 million unique users using a cryptocurrency wallet, most of them using bitcoin. The number of active users has grown since 2013. Bitcoins can be sold both on - and offline. Participants in online exchanges offer bitcoin sell bids. Using an online exchange to obtain bitcoins entails some risk, according to a study published in April 2013, 45% of exchanges fail and take client bitcoins with them. Exchanges have since implemented measures to provide proof of reserves in an effort to convey transparency to users. Offline, bitcoins may be purchased directly from an individual or at a bitcoin ATM. Bitcoin machines are not however traditional ATMs. Bitcoin kiosks are machines connected to the Internet, allowing the insertion of cash in exchange for bitcoins. Bitcoin kiosks do not connect to a bank and may charge transaction fees as high as 7% and exchange rates US$50 over rates from elsewhere.

As of 2016 it was estimated there were over 800 bitcoin ATMs operating globally, the majority being in the United States. According to Mark T. Williams, as of 2014, bitcoin has volatility seven times greater than gold, eight times greater than the S&P 500, 18 times greater than the U. S. dollar. Attempting to explain the high volatility, a group of Japanese scholars stated that there is no stabilization mechanism; the Bitcoin Foundation contends that high volatility is due to insufficient liquidity, while a Forbes journalist claims that it is related to the uncertainty of its long-term value, the high volatility of a startup currency makes sense, "because people are still experimenting with the currency to figure out how useful it is."There are uses where volatility does not matter, such as online gambling and international remittances. As of 2014, pro-bitcoin venture capitalists argued that the increased trading volume that planned high-frequency trading exchanges would generate is needed to decrease price volatility.

The price of bitcoins has gone through various cycles of appreciation and depreciation referred to by some as bubbles and busts. In 2011, the value of one bitcoin rose from about US$0.30 to US$32 before returning to US$2. In the latter half of 2012 and during the 2012–13 Cypriot financial crisis, the bitcoin price began to rise, reaching a high of US$266 on 10 April 2013, before crashing to around US$50. On 29 November 2013, the cost of one bitcoin rose to the all-time peak of US$

A univocalic is a type of antilipogrammatic constrained writing that uses only a single vowel, in English "A", "E", "I", "O", or "U", no others. One of the best-known univocalic poems was written by C. C. Bombaugh in 1890 using "O". Bombaugh's work is still in print. An example couplet:No cool monsoons blow soft on Oxford dons, jog-trot, book-worm SolomonsThe Austrian poet Ernst Jandl composed his univocalic poem "Ottos Mops" from German words with only the vowel "O". A contemporary example of English-language univocalic poems is Canadian poet Christian Bök's text Eunoia, published by Coach House Press in 2001; each chapter is restricted to a single vowel. For example the fourth chapter contains only "O". A typical sentence from this chapter is "Profs from Oxford show frosh who do post-docs how to gloss works of Wordsworth." An example of a univocalic novella is Georges Perec's Les Revenentes, in which the vowel "E" is used exclusively. The sentence Je cherche en même temps l'éternel et l'éphémère from this book has appeared as the epigraph for the last chapter of Life: a User's Manual.

Les Revenentes has been translated into English, titled "The Exeter Text: Jewels, Sex" using the vowel "E" exclusively. Georges Perec has written a univocalic in A and one in O. Höpöhöpö Böks by Icelandic poet Eiríkur Örn Norðdahl is a univocal lipogram using only the vowel Ö, it is composed as a tribute to Christian Bök's Eunoia. Eszperente is a univocalic form of Hungarian in which no vowels can be used other than "E"; this task is eased somewhat. In fact the letter e can denote two distinct vowels. There are poems and some books written in Eszperente for children. Argentinean folk singer Leon Gieco released a novelty song in 1997 called "Ojo con los Orozco", its describes the personalities and proclivities of eight fictional corrupt politicians, all brothers within the same family. The rap song is in Spanish, with a heavy dose of Lunfardo, some English words, a few pop culture references; the song's video makes heavy use of surrealistic images