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Stemplot
A stem-and-leaf display or stem-and-leaf plot is a device for presenting quantitative data in a graphical format, similar to a histogram, to assist in visualizing the shape of a distribution. They evolved from Arthur Bowley's work in the early 1900s, and are useful tools in exploratory data analysis. Stemplots became more commonly used in the 1980s after the publication of John Tukey's book on ''exploratory data analysis'' in 1977. The popularity during those years is attributable to their use of monospaced (typewriter) typestyles that allowed computer technology of the time to easily produce the graphics. Modern computers' superior graphic capabilities have meant these techniques are less often used. This plot has been implemented in Octave and R. A stem-and-leaf plot is also called a stemplot, but the latter term often refers to another chart type. A simple stem plot may refer to plotting a matrix of ''y'' values onto a common ''x'' axis, and identifying the common'' x'' value ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Exploratory Data Analysis
In statistics, exploratory data analysis (EDA) is an approach of analyzing data sets to summarize their main characteristics, often using statistical graphics and other data visualization methods. A statistical model can be used or not, but primarily EDA is for seeing what the data can tell us beyond the formal modeling and thereby contrasts traditional hypothesis testing. Exploratory data analysis has been promoted by John Tukey since 1970 to encourage statisticians to explore the data, and possibly formulate hypotheses that could lead to new data collection and experiments. EDA is different from initial data analysis (IDA), which focuses more narrowly on checking assumptions required for model fitting and hypothesis testing, and handling missing values and making transformations of variables as needed. EDA encompasses IDA. Overview Tukey defined data analysis in 1961 as: "Procedures for analyzing data, techniques for interpreting the results of such procedures, ways of pla ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Arthur Bowley
Sir Arthur Lyon Bowley, FBA (6 November 1869 – 21 January 1957) was an English statistician and economist who worked on economic statistics and pioneered the use of sampling techniques in social surveys. Early life Bowley's father, James William Lyon Bowley, was a minister in the Church of England. He died at the age of 40 when Arthur was one, leaving Arthur's mother as mother or stepmother to seven children. Arthur was educated at Christ's Hospital, and won a scholarship to Trinity College, Cambridge to study mathematics. He graduated as Tenth Wrangler. At Cambridge Bowley had a short course of study with the economist Alfred Marshall who had also been a Cambridge wrangler. Under Marshall's influence Bowley became an economic statistician. His ''Account of England's Foreign Trade'' won the Cobden Essay Prize and was published as a book. Marshall watched over Bowley's career, recommending him for jobs and offering him advice. Most notoriously Marshall told him the ''Element ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dot Plot (statistics)
A dot chart or dot plot is a statistical chart consisting of data points plotted on a fairly simple scale, typically using filled in circles. There are two common, yet very different, versions of the dot chart. The first has been used in hand-drawn (pre-computer era) graphs to depict distributions going back to 1884. The other version is described by William S. Cleveland as an alternative to the bar chart, in which dots are used to depict the quantitative values (e.g. counts) associated with categorical variables. Of a distribution The dot plot as a representation of a distribution consists of group of data points plotted on a simple scale. Dot plots are used for continuous, quantitative, univariate data. Data points may be labelled if there are few of them. Dot plots are one of the simplest statistical plots, and are suitable for small to moderate sized data sets. They are useful for highlighting clusters and gaps, as well as outliers. Their other advantage is the conservation of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stem Leaf Plot 001
Stem or STEM may refer to: Plant structures * Plant stem, a plant's aboveground axis, made of vascular tissue, off which leaves and flowers hang * Stipe (botany), a stalk to support some other structure * Stipe (mycology), the stem of a mushroom under the cap * Stem (vine), part of a grapevine * Trunk (botany), the woody stem of a tree Education * Science, technology, engineering, and mathematics (STEM), a broad term used in curricula and policy * STEM.org, an educational publisher and service * Stem, a multiple choice question lede (excluding the options) Language and writing * Word stem, the part of a word common to all its inflected variants ** Stemming, a process in natural language processing * Stem (typography), the main vertical stroke of a letter * Stem (music), a part of a written musical note Man-made objects * Stem (ship), the upright member mounted on the forward end of a vessel's keel, to which the strakes are attached * Stem (bicycle part), connects the ha ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Place Value
Positional notation (or place-value notation, or positional numeral system) usually denotes the extension to any base of the Hindu–Arabic numeral system (or decimal system). More generally, a positional system is a numeral system in which the contribution of a digit to the value of a number is the value of the digit multiplied by a factor determined by the position of the digit. In early numeral systems, such as Roman numerals, a digit has only one value: I means one, X means ten and C a hundred (however, the value may be negated if placed before another digit). In modern positional systems, such as the decimal system, the position of the digit means that its value must be multiplied by some value: in 555, the three identical symbols represent five hundreds, five tens, and five units, respectively, due to their different positions in the digit string. The Babylonian numeral system, base 60, was the first positional system to be developed, and its influence is present today ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Initial
In a written or published work, an initial capital, also referred to as a drop capital or simply an initial cap, initial, initcapital, initcap or init or a drop cap or drop, is a letter at the beginning of a word, a chapter, or a paragraph that is larger than the rest of the text. The word is derived from the Latin ''initialis'', which means ''standing at the beginning''. An initial is often several lines in height and in older books or manuscripts are known as "inhabited" initials. Certain important initials, such as the Beatus initial or "B" of ''Beatus vir...'' at the opening of Psalm 1 at the start of a vulgate Latin. These specific initials in an illuminated manuscript were also called initiums. In the present, the word "initial" commonly refers to the first letter of any word or name, the latter normally capitalized in English usage and is generally that of a first given name or a middle one or ones. History The classical tradition was slow to use capital letters fo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Scrabble
''Scrabble'' is a word game in which two to four players score points by placing tiles, each bearing a single letter, onto a game board divided into a 15×15 grid of squares. The tiles must form words that, in crossword fashion, read left to right in rows or downward in columns and are included in a standard dictionary or lexicon. The name ''Scrabble'' is a trademark of Mattel in most of the world, except in the United States and Canada, where it is a trademark of Hasbro, under the brands of both of its subsidiaries, Milton Bradley and Parker Brothers. The game is sold in 121 countries and is available in more than 30 languages; approximately 150 million sets have been sold worldwide, and roughly one-third of American and half of British homes have a ''Scrabble'' set. There are approximately 4,000 ''Scrabble'' clubs around the world. Game details The game is played by two to four players on a square game board imprinted with a 15×15 grid of cells (individually known as " ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Collins Scrabble Words
Collins Scrabble Words (CSW, formerly SOWPODS) is the word list used in English-language tournament Scrabble in most countries except the US, Thailand and Canada. The term SOWPODS is an anagram of the two abbreviations '' OSPD'' (Official Scrabble Players Dictionary) and '' OSW'' (Official Scrabble Words), these being the original two official dictionaries used in various parts of the world at the time. Although the two source dictionaries have now changed their respective titles, the term SOWPODS is still used by tournament players to refer to the combination of the two sources. There has not been any actual hard-copy list produced called SOWPODS, although the current Collins Scrabble Words, or CSW, is in effect the full SOWPODS list by a different name. Currently the two main sources for the words making up the combined list (generally known as Collins) are: * The British words. Derived from two sources; the ''Collins English Dictionary'' and the ''Collins Corpus'', and * The Ame ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Box Plot
In descriptive statistics, a box plot or boxplot is a method for graphically demonstrating the locality, spread and skewness groups of numerical data through their quartiles. In addition to the box on a box plot, there can be lines (which are called ''whiskers'') extending from the box indicating variability outside the upper and lower quartiles, thus, the plot is also termed as the box-and-whisker plot and the box-and-whisker diagram. Outliers that differ significantly from the rest of the dataset may be plotted as individual points beyond the whiskers on the box-plot. Box plots are non-parametric: they display variation in samples of a statistical population without making any assumptions of the underlying statistical distribution (though Tukey's boxplot assumes symmetry for the whiskers and normality for their length). The spacings in each subsection of the box-plot indicate the degree of dispersion (spread) and skewness of the data, which are usually described using the five ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mode (statistics)
The mode is the value that appears most often in a set of data values. If is a discrete random variable, the mode is the value (i.e, ) at which the probability mass function takes its maximum value. In other words, it is the value that is most likely to be sampled. Like the statistical mean and median, the mode is a way of expressing, in a (usually) single number, important information about a random variable or a population. The numerical value of the mode is the same as that of the mean and median in a normal distribution, and it may be very different in highly skewed distributions. The mode is not necessarily unique to a given discrete distribution, since the probability mass function may take the same maximum value at several points , , etc. The most extreme case occurs in uniform distributions, where all values occur equally frequently. When the probability density function of a continuous distribution has multiple local maxima it is common to refer to all of the local ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Outlier
In statistics, an outlier is a data point that differs significantly from other observations. An outlier may be due to a variability in the measurement, an indication of novel data, or it may be the result of experimental error; the latter are sometimes excluded from the data set. An outlier can be an indication of exciting possibility, but can also cause serious problems in statistical analyses. Outliers can occur by chance in any distribution, but they can indicate novel behaviour or structures in the data-set, measurement error, or that the population has a heavy-tailed distribution. In the case of measurement error, one wishes to discard them or use statistics that are robust to outliers, while in the case of heavy-tailed distributions, they indicate that the distribution has high skewness and that one should be very cautious in using tools or intuitions that assume a normal distribution. A frequent cause of outliers is a mixture of two distributions, which may be two dist ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Non-parametric Statistics
Nonparametric statistics is the branch of statistics that is not based solely on parametrized families of probability distributions (common examples of parameters are the mean and variance). Nonparametric statistics is based on either being distribution-free or having a specified distribution but with the distribution's parameters unspecified. Nonparametric statistics includes both descriptive statistics and statistical inference. Nonparametric tests are often used when the assumptions of parametric tests are violated. Definitions The term "nonparametric statistics" has been imprecisely defined in the following two ways, among others: Applications and purpose Non-parametric methods are widely used for studying populations that take on a ranked order (such as movie reviews receiving one to four stars). The use of non-parametric methods may be necessary when data have a ranking but no clear numerical interpretation, such as when assessing preferences. In terms of levels of me ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
