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Tolerance Interval A TOLERANCE INTERVAL is a statistical interval within which, with some confidence level, a specified proportion of a sampled population falls. "More speciﬁcally, a 100×p%/100×(1−α) tolerance interval provides limits within which at least a certain proportion (p) of the population falls with a given level of conﬁdence (1−α)." "A (p, 1−α) tolerance interval (TI) based on a sample is constructed so that it would include at least a proportion p of the sampled population with conﬁdence 1−α; such a TI is usually referred to as pcontent − (1−α) coverage TI." "A (p, 1−α) upper TOLERANCE LIMIT (TL) is simply an 1−α upper confidence limit for the 100 p percentile of the population." A tolerance interval can be seen as a statistical version of a probability interval [...More...]  "Tolerance Interval" on: Wikipedia Yahoo 

Central Limit Theorem In probability theory , the CENTRAL LIMIT THEOREM (CLT) establishes that, in most situations, when independent random variables are added, their properly normalized sum tends toward a normal distribution (a bell curve) even if the original variables themselves are not normally distributed. The theorem is a key concept in probability theory because it implies that probabilistic and statistical methods that work for normal distributions can be applicable to many problems involving other types of distributions. For example, suppose that a sample is obtained containing a large number of observations , each observation being randomly generated in a way that does not depend on the values of the other observations, and that the arithmetic average of the observed values is computed. If this procedure is performed many times, the central limit theorem says that the computed values of the average will be distributed according to a normal distribution [...More...]  "Central Limit Theorem" on: Wikipedia Yahoo 

Fuel Economy In Automobiles The FUEL ECONOMY of an automobile is the fuel efficiency relationship between the distance traveled and the amount of fuel consumed by the vehicle. Consumption can be expressed in terms of volume of fuel to travel a distance, or the distance travelled per unit volume of fuel consumed. Since fuel consumption of vehicles is a significant factor in air pollution, and since importation of motor fuel can be a large part of a nation's foreign trade, many countries impose requirements for fuel economy. Different measurement cycles are used to approximate the actual performance of the vehicle. The energy in fuel is required to overcome various losses (wind resistance, tire drag, and others) in propelling the vehicle, and in providing power to vehicle systems such as ignition or air conditioning. Various measures can be taken to reduce losses at each of the conversions between chemical energy in fuel and kinetic energy of the vehicle [...More...]  "Fuel Economy In Automobiles" on: Wikipedia Yahoo 

United States Environmental Protection Agency The UNITED STATES ENVIRONMENTAL PROTECTION AGENCY (EPA or sometimes USEPA) is an agency of the federal government of the United States which was created for the purpose of protecting human health and the environment by writing and enforcing regulations based on laws passed by Congress . President Richard Nixon proposed the establishment of EPA and it began operation on December 2, 1970, after Nixon signed an executive order . The order establishing the EPA was ratified by committee hearings in the House and Senate. The agency is led by its Administrator , who is appointed by the President and approved by Congress. The current Administrator is Scott Pruitt . The EPA is not a Cabinet department, but the Administrator is normally given cabinet rank . The EPA has its headquarters in Washington, D.C. , regional offices for each of the agency's ten regions , and 27 laboratories. The agency conducts environmental assessment, research, and education [...More...]  "United States Environmental Protection Agency" on: Wikipedia Yahoo 

Digital Object Identifier In computing, a DIGITAL OBJECT IDENTIFIER or DOI is a persistent identifier or handle used to uniquely identify objects, standardized by the ISO ISO . An implementation of the Handle System , DOIs are in wide use mainly to identify academic, professional, and government information, such as journal articles, research reports and data sets, and official publications though they also have been used to identify other types of information resources, such as commercial videos. A DOI aims to be "resolvable", usually to some form of access to the information object to which the DOI refers. This is achieved by binding the DOI to metadata about the object, such as a URL , indicating where the object can be found. Thus, by being actionable and interoperable, a DOI differs from identifiers such as ISBNs and ISRCs which aim only to uniquely identify their referents. The DOI system uses the indecs Content Model for representing metadata [...More...]  "Digital Object Identifier" on: Wikipedia Yahoo 

International Standard Book Number The INTERNATIONAL STANDARD BOOK NUMBER (ISBN) is a unique numeric commercial book identifier. An ISBN is assigned to each edition and variation (except reprintings) of a book. For example, an ebook , a paperback and a hardcover edition of the same book would each have a different ISBN. The ISBN is 13 digits long if assigned on or after 1 January 2007, and 10 digits long if assigned before 2007. The method of assigning an ISBN is nationbased and varies from country to country, often depending on how large the publishing industry is within a country. The initial ISBN configuration of recognition was generated in 1967 based upon the 9digit STANDARD BOOK NUMBERING (SBN) created in 1966. The 10digit ISBN format was developed by the International Organization for Standardization (ISO) and was published in 1970 as international standard ISO 2108 (the SBN code can be converted to a ten digit ISBN by prefixing it with a zero) [...More...]  "International Standard Book Number" on: Wikipedia Yahoo 

International Standard Serial Number An INTERNATIONAL STANDARD SERIAL NUMBER (ISSN) is an eightdigit serial number used to uniquely identify a serial publication . The ISSN is especially helpful in distinguishing between serials with the same title. ISSN are used in ordering, cataloging, interlibrary loans, and other practices in connection with serial literature. The ISSN system was first drafted as an International Organization for Standardization (ISO) international standard in 1971 and published as ISO 3297 in 1975. ISO subcommittee TC 46/SC 9 is responsible for maintaining the standard. When a serial with the same content is published in more than one media type , a different ISSN is assigned to each media type. For example, many serials are published both in print and electronic media . The ISSN system refers to these types as PRINT ISSN (PISSN) and ELECTRONIC ISSN (EISSN), respectively [...More...]  "International Standard Serial Number" on: Wikipedia Yahoo 

JSTOR JSTOR JSTOR (/ˈdʒeɪstɔːr/ JAYstor ; short for Journal Storage) is a digital library founded in 1995. Originally containing digitized back issues of academic journals , it now also includes books and primary sources, and current issues of journals. It provides fulltext searches of almost 2,000 journals. As of 2013, more than 8,000 institutions in more than 160 countries had access to JSTOR; most access is by subscription, but some older public domain content is freely available to anyone. JSTOR's revenue was $69 million in 2014. CONTENTS * 1 History * 2 Content * 3 Access * 3.1 Aaron Swartz Aaron Swartz incident * 3.2 Limitations * 3.3 Increasing public access * 4 Use * 5 See also * 6 References * 7 Further reading * 8 External links HISTORY William G. Bowen , president of Princeton University Princeton University from 1972 to 1988, founded JSTOR [...More...]  "JSTOR" on: Wikipedia Yahoo 

Special SPECIAL or SPECIALS may refer to: CONTENTS * 1 Music * 2 Film and television * 3 Other uses * 4 See also MUSIC * Special (album) , a 1992 album by Vesta Williams * "Special" (Garbage song) , 1998 * "Special" (Mew song) , 2005 * "Special" (Stephen Lynch song) , 2000 * The Specials The Specials , a British band * "Special", a song by Violent Femmes on The Blind Leading the Naked * "Special", a song on [...More...]  "Special" on: Wikipedia Yahoo 

Sample Mean The SAMPLE MEAN or EMPIRICAL MEAN and the SAMPLE COVARIANCE are statistics computed from a collection (the sample ) of data on one or more random variables . The sample mean and sample covariance are estimators of the population mean and population covariance , where the term population refers to the set from which the sample was taken. The sample mean is a vector each of whose elements is the sample mean of one of the random variables – that is, each of whose elements is the arithmetic average of the observed values of one of the variables. The sample covariance matrix is a square matrix whose i, j element is the sample covariance (an estimate of the population covariance) between the sets of observed values of two of the variables and whose i, i element is the sample variance of the observed values of one of the variables [...More...]  "Sample Mean" on: Wikipedia Yahoo 

Lognormal Distribution In probability theory , a LOGNORMAL (OR LOGNORMAL) DISTRIBUTION is a continuous probability distribution of a random variable whose logarithm is normally distributed . Thus, if the random variable X is lognormally distributed, then Y = ln(X) has a normal distribution. Likewise, if Y has a normal distribution, then the exponential function of Y, X = exp(Y), has a lognormal distribution. A random variable which is lognormally distributed takes only positive real values. The distribution is occasionally referred to as the GALTON DISTRIBUTION or GALTON\'S DISTRIBUTION, after Francis Galton . The lognormal distribution also has been associated with other names, such as McAlister, Gibrat and Cobb–Douglas . A lognormal process is the statistical realization of the multiplicative product of many independent random variables , each of which is positive. This is justified by considering the central limit theorem in the log domain [...More...]  "Lognormal Distribution" on: Wikipedia Yahoo 

Count Data In statistics , COUNT DATA is a statistical data type , a type of data in which the observations can take only the nonnegative integer values {0, 1, 2, 3, ...}, and where these integers arise from counting rather than ranking . The statistical treatment of count data is distinct from that of binary data , in which the observations can take only two values, usually represented by 0 and 1, and from ordinal data , which may also consist of integers but where the individual values fall on an arbitrary scale and only the relative ranking is important. Statistical analyses involving count data includes simple counts, such as the number of occurrences of thunderstorms in a calendar year, and categorical data in which the counts represent the numbers of items falling into each of several categories [...More...]  "Count Data" on: Wikipedia Yahoo 

Noncentral Chisquared Distribution k > 0 {displaystyle k>0,} degrees of freedom > 0 {displaystyle lambda >0,} noncentrality parameter SUPPORT x Let ( X 1 , X 2 , , X i , , X k {displaystyle (X_{1},X_{2},ldots ,X_{i},ldots ,X_{k}} ) be k independent , normally distributed random variables with means i {displaystyle mu _{i}} and unit variances. Then the random variable i = 1 k X i 2 {displaystyle sum _{i=1}^{k}X_{i}^{2}} is distributed according to the noncentral chisquared distribution. It has two parameters: k {displaystyle k} which specifies the number of degrees of freedom (i.e. the number of X i {displaystyle X_{i}} ), and {displaystyle lambda } which is related to the mean of the random variables X i {displaystyle X_{i}} by: = i = 1 k i 2 [...More...]  "Noncentral Chisquared Distribution" on: Wikipedia Yahoo 

Normal Distribution In probability theory , the NORMAL (or GAUSSIAN) DISTRIBUTION is a very common continuous probability distribution . Normal distributions are important in statistics and are often used in the natural and social sciences to represent realvalued random variables whose distributions are not known. The normal distribution is useful because of the central limit theorem . In its most general form, under some conditions (which include finite variance ), it states that averages of samples of observations of random variables independently drawn from independent distributions converge in distribution to the normal, that is, become normally distributed when the number of observations is sufficiently large. Physical quantities that are expected to be the sum of many independent processes (such as measurement errors ) often have distributions that are nearly normal [...More...]  "Normal Distribution" on: Wikipedia Yahoo 

Interquartile Range In descriptive statistics , the INTERQUARTILE RANGE (IQR), also called the MIDSPREAD or MIDDLE 50%, or technically HSPREAD, is a measure of statistical dispersion , being equal to the difference between 75th and 25th percentiles , or between upper and lower quartiles , IQR = Q3 − Q1. In other words, the IQR is the first quartile subtracted from the third quartile; these quartiles can be clearly seen on a box plot on the data. It is a trimmed estimator , defined as the 25% trimmed range , and is the most significant basic robust measure of scale . The IQR is a measure of variability, based on dividing a data set into quartiles. Quartiles divide a rankordered data set into four equal parts. The values that separate parts are called the first, second, and third quartiles; and they are denoted by Q1, Q2, and Q3, respectively [...More...]  "Interquartile Range" on: Wikipedia Yahoo 

Correlation And Dependence In statistics , DEPENDENCE or ASSOCIATION is any statistical relationship, whether causal or not, between two random variables or bivariate data . CORRELATION is any of a broad class of statistical relationships involving dependence, though in common usage it most often refers to the extent to which two variables have a linear relationship with each other. Familiar examples of dependent phenomena include the correlation between the physical statures 