In Search of Reliable Internet Measurement Data Newspapers and magazines frequently report growth rates of Internet usage, number of users, hosts, and domains that seem to be beyond all expectations. Growth rates are expected to accelerate exponentially. However, Internet measurement data are anything thant reliable and often quite fantastic constructs, that are nevertheless jumped upon by many media and decision makers because the technical difficulties in measuring Internet growth or usage are make reliable measurement techniques impossible. Equally, predictions that the Internet is about to collapse lack any foundation whatsoever. The researchers at the Size and Growth In fact, "today's Internet industry lacks any ability to evaluate trends, identity performance problems beyond the boundary of a single ISP (Internet service provider, M. S.), or prepare systematically for the growing expectations of its users. Historic or current data about traffic on the Internet infrastructure, maps depicting ... there is plenty of measurement occurring, albeit of questionable quality", says K. C. Claffy in his paper Internet measurement and data analysis: topology, workload, performance and routing statistics (http://www.caida.org/Papers/Nae/, Dec 6, 1999). Claffy is not an average researcher; he founded the well-known So his statement is a slap in the face of all market researchers stating otherwise. In a certain sense this is ridiculous, because since the inception of the So what are the reasons for this inability to evaluate trends, identity performance problems beyond the boundary of a single ISP? First, in early 1995, almost simultaneously with the worldwide introduction of the "There are many estimates of the size and growth rate of the Internet that are either implausible, or inconsistent, or even clearly wrong", K. G. Coffman and Andrew, both members of different departments of What is measured and what methods are used? Many studies are devoted to the number of users; others look at the number of computers connected to the Internet or count You get the clue of their focus when you bear in mind that the Internet is just one of many networks of networks; it is only a part of the universe of computer networks. Additionally, the Internet has public (unrestricted) and private (restricted) areas. Most studies consider only the public Internet, Coffman and Odlyzko consider the long-distance private line networks too: the corporate networks, the Hosts The Despite the small sample, this method has at least one flaw: Internet Weather Like daily weather, traffic on the Internet, the conditions for data flows, are monitored too, hence called Internet weather. One of the most famous Internet Hits, Page Views, Visits, and Users Let us take a look at how these hot lists of most visited Web sites may be compiled. I say, may be, because the methods used for data retrieval are mostly not fully disclosed. For some years it was seemingly common sense to report requested files from a Web site, so called "hits". A method not very useful, because a document can consist of several files: graphics, text, etc. Just compile a document from some text and some twenty flashy graphical files, put it on the Web and you get twenty-one hits per visit; the more graphics you add, the more hits and traffic (not automatically to your Web site) you generate. In the meantime page views, also called page impressions are preferred, which are said to avoid these flaws. But even page views are not reliable. Users might share computers and corresponding Especially the editors of some electronic journals (e-journals) rely on page views as a kind of ratings or circulation measure, Rick Marin reports in the More advanced, but just slightly better at best, is counting visits, the access of several pages of a Web site during one session. The problems already mentioned apply here too. To avoid them, newspapers, e.g., establish registration services, which require password authentication and therefore prove to be a kind of access obstacle. But there is a different reason for these services. For content providers users are virtual users, not unique persons, because, as already mentioned, computers and For If you like to play around with Internet statistics instead, you can use Robert Orenstein's Measuring the Density of Measuring the Density of Dodge and Shiode used data on the ownership of IP addresses from |
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The 19th Century: First Programmable Computing Devices Until the 19th century "early computers", probably better described as calculating machines, were basically mechanical devices and operated by hand. Early Therefore After working on the Difference Engine for ten years Babbage was inspired to build another machine, which he called Analytical Engine. Its invention was a major step towards the design of modern computers, as it was conceived the first general-purpose computer. Instrumental to the machine's design was his assistant, Augusta Ada King, Countess of Lovelace, the first female computer programmer. The second major breakthrough in the design of computing machines in the 19th century may be attributed to the American inventor Herman Hollerith. He was concerned with finding a faster way to compute the U.S. census, which in 1880 had taken nearly seven years. Therefore Hollerith invented a method, which used cards to store data information which he fed into a machine that compiled the results automatically. The punch cards not only served as a storage method and helped reduce computational errors, but furthermore significantly increased speed. Of extraordinary importance for the evolution of digital computers and |
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John von Neumann b. December 3, 1903, Budapest, Hungary d. February 8, 1957, Washington, D.C., U.S. Mathematician who made important contributions in quantum physics, logic, meteorology, and computer science. His theory of games had a significant influence upon economics. In computer theory, von Neumann did much of the pioneering work in logical design, in the problem of obtaining reliable answers from a machine with unreliable components, the function of "memory," machine imitation of "randomness," and the problem of constructing automata that can reproduce their own kind. |
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UNIVAC Built by Remington Rand in 1951 the UNIVAC I (Universal Automatic Computer) was one of the first commercially available computers to take advantage of the development of the |
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Alan Turing b. June 23, 1912, London, England d. June 7, 1954, Wilmslow, Cheshire English mathematician and logician who pioneered in the field of computer theory and who contributed important logical analyses of computer processes. Many mathematicians in the first decades of the 20th century had attempted to eliminate all possible error from mathematics by establishing a formal, or purely algorithmic, procedure for establishing truth. The mathematician Kurt Gödel threw up an obstacle to this effort with his incompleteness theorem. Turing was motivated by Gödel's work to seek an algorithmic method of determining whether any given propositions were undecidable, with the ultimate goal of eliminating them from mathematics. Instead, he proved in his seminal paper "On Computable Numbers, with an Application to the Entscheidungsproblem [Decision Problem]" (1936) that there cannot exist any such universal method of determination and, hence, that mathematics will always contain undecidable propositions. During World War II he served with the Government Code and Cypher School, at Bletchley, Buckinghamshire, where he played a significant role in breaking the codes of the German " |
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Bandwidth The bandwidth of a transmitted communications signal is a measure of the range of frequencies the signal occupies. The term is also used in reference to the frequency-response characteristics of a communications receiving system. All transmitted signals, whether analog or digital, have a certain bandwidth. The same is true of receiving systems. Generally speaking, bandwidth is directly proportional to the amount of data transmitted or received per unit time. In a qualitative sense, bandwidth is proportional to the complexity of the data for a given level of system performance. For example, it takes more bandwidth to download a photograph in one second than it takes to download a page of text in one second. Large sound files, computer programs, and animated videos require still more bandwidth for acceptable system performance. Virtual reality (VR) and full-length three-dimensional audio/visual presentations require the most bandwidth of all. In digital systems, bandwidth is data speed in bits per second (bps). Source: Whatis.com |
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