Editing Chart

{{short description|Graphical representation of data}}
{{other uses|Chart (disambiguation)|Graph (disambiguation)|Diagram}}
{{More citations needed|date=October 2011}}
[[File:Composition of 38th Parliament.svg|class=skin-invert-image|thumb|A [[pie chart]] showing the composition of the [[38th Canadian Parliament|38th]] Parliament of Canada]]

A '''chart''' (sometimes known as a '''graph''') is a [[graphics|graphical representation]] for [[data visualization]], in which "the [[data]] is represented by [[symbol]]s, such as bars in a [[bar chart]], lines in a [[line chart]], or slices in a [[pie chart]]".<ref>Cary Jensen, Loy Anderson (1992). ''Harvard graphics 3: the complete reference''. Osborne McGraw-Hill {{ISBN|0-07-881749-8}} p.413</ref> A chart can represent [[Table (information)|tabular]] [[number|numeric]] data, [[Graph of a function|functions]] or some kinds of [[Quality of service|quality]] structure and provides different info.

The term "chart" as a graphical representation of [[data]] has multiple meanings:
* A data chart is a type of [[diagram]] or [[Graph of a function|graph]], that organizes and represents a set of numerical or qualitative data.
* [[Map]]s that are adorned with extra information ([[map surround]]) for a specific purpose are often known as charts, such as a [[nautical chart]] or [[aeronautical chart]], typically spread over several [[map sheet]]s.
* Other domain-specific constructs are sometimes called charts, such as the [[chord chart]] in music notation or a [[record chart]] for album popularity.

Charts are often used to ease understanding of large quantities of data and the relationships between parts of the data. Charts can usually be read more quickly than the raw data. They are used in a wide variety of fields, and can be created by hand (often on [[graph paper]]) or by computer using a [[charting application]]. Certain types of charts are more useful for presenting a given data set than others. For example, data that presents [[percentage]]s in different groups (such as "satisfied, not satisfied, unsure") are often displayed in a [[pie chart]], but maybe more easily understood when presented in a horizontal [[bar chart]].<ref>[[Howard Wainer]] (1997) ''Visual revelations: graphical tales of fate and Deception from Napoleon Bonaparte to Ross Perot'', Lawrence Erlbaum Associates, Inc. {{ISBN|0-8058-3878-3}} p.87-90.</ref> On the other hand, data that represents numbers that change over a period of time (such as "annual revenue from 1990 to 2000") might be best shown as a [[line chart]].

== Features ==
A chart can take a large variety of forms. However, there are common features that provide the chart with its ability to extract meaning from data.

Typically the data in a chart is represented graphically since humans can infer meaning from pictures more quickly than from text. Thus, the text is generally used only to annotate the data.

One of the most important uses of text in a graph is the '''title'''. A graph's title usually appears above the main graphic and provides a succinct description of what the data in the graph refers to.

Dimensions in the data are often displayed on '''[[X axis|axes]]'''. If a horizontal and a vertical axis are used, they are usually referred to as the x-axis and y-axis. Each axis will have a '''scale''', denoted by periodic graduations and usually accompanied by numerical or categorical indications. Each axis will typically also have a label displayed outside or beside it, briefly describing the dimension represented. If the scale is numerical, the label will often be suffixed with the unit of that scale in parentheses. For example, "Distance traveled (m)" is a typical x-axis label and would mean that the distance traveled, in units of meters, is related to the horizontal position of the data within the chart.

Within the graph, a '''grid''' of lines may appear to aid in the visual alignment of data. The grid can be enhanced by visually emphasizing the lines at regular or significant graduations. The emphasized lines are then called major gridlines, and the remainder is minor grid lines.

A chart's data can appear in all manner of formats and may include individual textual '''labels''' describing the datum associated with the indicated position in the chart. The data may appear as dots or shapes, connected or unconnected, and in any combination of colors and patterns. In addition, inferences or points of interest can be overlaid directly on the graph to further aid information extraction.

When the data appearing in a chart contains multiple variables, the chart may include a '''legend''' (also known as a '''key'''). A legend contains a list of the variables appearing in the chart and an example of their appearance. This information allows the data from each variable to be identified in the chart.

== Types ==
{{disputed|reason=4 of the "most common charts" is totally unverified claim. Likewise the "also common" and the "less common" categorization of the various charts.|date=October 2019}}
{{See also|Commons:Category:Charts by type}}

=== Common charts ===
Four of the most common charts are:

<gallery class="skin-invert-image">
File:Black cherry tree histogram.svg|[[Histogram]]
File:Försäljningsstatistik för blanddrycker.png|[[Bar chart]]
File:ActionnariatLibe2007-fr.svg|[[Pie chart]]
File:US Trade Balance from 1960.svg|[[Line chart]]

</gallery>

This gallery shows:

* A [[histogram]] consists of tabular frequencies, shown as adjacent rectangles, erected over discrete intervals (bins), with an area equal to the frequency of the observations in the interval; first introduced by Karl Pearson.<ref name="pearson">{{Cite journal| last1 = Pearson | first1 = K. |author-link=Karl Pearson| title = Contributions to the Mathematical Theory of Evolution. II. Skew Variation in Homogeneous Material| journal = Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences| volume = 186| pages = 343–414| year = 1895| doi = 10.1098/rsta.1895.0010|bibcode = 1895RSPTA.186..343P | url = https://zenodo.org/record/1432104| doi-access = free}}</ref>
* A [[bar chart]] is a chart with rectangular bars with lengths proportional to the values that they represent. The bars can be plotted vertically or horizontally. The first known bar charts are usually attributed to Nicole Oresme, Joseph Priestley, and William Playfair.<ref>{{cite web|title=First Ever Bar Charts Created in 14th Century|date=2 June 2015 |url=http://www.anychart.com/blog/2015/06/02/first-bar-chart-in-history/|publisher=AnyChart|access-date=9 February 2016}}</ref>
* A [[pie chart]] shows percentage values as a slice of a pie; first introduced by William Playfair.<ref>{{cite web|url=http://www.jpowered.com/graphs-and-charts/pie-chart-history.htm|title=History of Pie Charts|publisher=JPowered|access-date=9 February 2016|archive-url=https://web.archive.org/web/20160115164419/http://jpowered.com/graphs-and-charts/pie-chart-history.htm|archive-date=15 January 2016|url-status=dead}}</ref>
* A [[line chart]] is a two-dimensional scatterplot of ordered observations where the observations are connected following their order. The first known line charts are usually credited to Francis Hauksbee, Nicolaus Samuel Cruquius, Johann Heinrich Lambert and William Playfair.<ref>{{cite web|author=Michael Friendly|year=2008|url=http://www.math.yorku.ca/SCS/Gallery/milestone/milestone.pdf|title=Milestones in the history of thematic cartography, statistical graphics, and data visualization|pages=13–14|author-link=Michael Friendly}}</ref>
Other common charts are:

<gallery class="skin-invert-image">
File:BTTFTimelines.png|[[Timeline]] chart
File:Organigram of the United States Department of the Navy.gif|[[Organizational chart]]
File:ABB.svg|Tree chart
File:Flussdiagramm (Programmablaufplan).png|[[Flow chart]]
File:MLB slugging history.svg|[[Area chart]]
File:Cartlinearlarge.png|[[Cartogram]]
File:Autosomal Dominant Pedigree Chart.svg|[[Pedigree chart]]
File:Sunburst Chart.jpg|[[Radial tree]]
</gallery>

=== Less-common charts ===
Examples of less common charts are:

<gallery class="skin-invert-image">
File:3Variable_BubbleChart.svg|[[Bubble chart]]
File:Nightingale-mortality.jpg|[[Pie chart#Polar area diagram|Polar area diagram]]
File:Waterfall-chart.jpg|[[Waterfall chart]]
File:Fuentes de consumo de energía diaria 2001-2003 (FAO).svg|[[Radar chart]]
File:Heatmap incito.png|[[Treemapping|Tree map]]
File:LastGraph example.svg|[[Streamgraph]]
File:GapChart-Top14-2013-2014.png|GapChart
</gallery>

This gallery shows:
* A [[bubble chart]] is a two-dimensional scatterplot where a third variable is represented by the size of the points.
* A [[Pie chart#Polar area diagram|polar area diagram]], sometimes called a Coxcomb chart, is an enhanced form of pie chart developed by [[Florence Nightingale]].
* A [[radar chart]] or "spider chart" or "doi" is a two-dimensional chart of three or more quantitative variables represented on axes starting from the same point.
* A [[waterfall chart]] also known as a "Walk" chart, is a special type of floating-column chart.
* A [[Treemapping|tree map]] where the areas of the rectangles correspond to values.  Other dimensions can be represented with color or hue. Smaller areas go to the bottom right corner.
* A [[streamgraph]], a stacked, curvilinear area graph displaced around a central axis
* A GapChart, a time series chart showing evolving gaps and equalities between series. Other dimensions can be represented with color or hue.

=== Field-specific charts ===
Some types of charts have specific uses in a certain field

<gallery class="skin-invert-image">
File:Bollinger bands example, 2 stddevs.png|[[Open-high-low-close chart]]
File:Candlestick-chart.png|[[Candlestick chart]]
File:KagiSample2Chart echarts.gif|[[Kagi chart]]
File:Sparkline dowjones.svg|[[Sparkline]]
</gallery>

This gallery shows:
* Stock market prices are often depicted with an [[open-high-low-close chart]] with a traditional bar chart of volume at the bottom.
* [[Candlestick chart]]s are another type of bar chart used to describe price movements of an equity over time.
* A [[Kagi chart]] is a time-independent stock tracking chart that attempts to minimise noise.
* Alternatively, where less detail is required, and chart size is paramount, a [[Sparkline]] may be used.

Other examples:
* Interest rates, temperatures, etc., at the close of the period are plotted with a line chart.
* Project planners use a [[Gantt chart]] to show the timing of tasks as they occur over time.

=== Well-known named charts ===
Some of the better-known named charts are:

<gallery class="skin-invert-image">
File:Gantt przyklad 2.PNG|[[Gantt chart]]
File:Nolan-chart.svg|[[Nolan chart]]
File:5n PERT graph with critical path.svg|[[PERT]] chart
File:Smith chart bmd.gif|[[Smith chart]]
</gallery>

Some specific charts have become well known by effectively explaining a phenomenon or idea.
* An [[Allele chart]] is a chart originating from the study of [[genetics]] to show the interaction of two data points in a grid.
* A [[Gantt chart]] helps in scheduling complex projects.
* The [[Nolan chart]] and the [[Pournelle chart]] classify political philosophies according to two axes of variation.
* A [[Program Evaluation and Review Technique|PERT chart]] is often used in [[project management]].
* The [[Smith chart]] serves in [[radio electronics]].

=== Other charts ===
There are dozens of other types of charts. Here are some of them:

<gallery class="skin-invert-image">
File:ControlChart.svg|[[Control chart]]
File:GreningerChart.png|[[Greninger chart]]
File:Heatmap.png|[[Heatmap]]
File:Horoscope-Christ.jpg|[[Natal chart]]
File:TS-Wasserdampf. neu.png|[[Nomogram]]
File:800px-Pareto fr.png|[[Pareto chart]]
File:SimpleRunChart.jpg|[[Run chart]]
File:Example Strip Chart.png|Strip chart
File:Configuration System Structure Chart.jpg|[[Structure chart]]
File:Amharic vowel chart.svg|[[Vowel chart]]
</gallery>

One more example: [[Bernal chart]]

=== Common plots ===
{{main|Plot (graphics)}}

<gallery class="skin-invert-image">
File:Michelsonmorley-boxplot.svg|[[Box plot]]
File:Dotplot of random values 2.png|[[Dot plot (statistics)]]
File:Probability Plot.gif|[[Probability plot correlation coefficient plot|Probability plot]]
File:oldfaithful3.png|[[Scatterplot]]
File:Spectramap Biplot Iris Flower Data Set FULL.jpg|[[Biplot]]
</gallery>

== Chart software ==
While charts can be drawn by hand, computer software is often used to automatically produce a chart based on entered data. For examples of commonly used software tools, see [[List of charting software]].

==See also==
{{commons}}
* [[Diagram]]
* [[Table (information)]]
* [[DRAKON|Drakon-chart]]
* [[Exploratory data analysis]]
* [[Graphic organizer]]
* [[Information graphics]]
* [[Mathematical diagram]]
* [[Official statistics]]
* [[Plot (graphics)]]
* [[Edward Tufte]]
* [[Misleading graph]]

== References ==
{{reflist}}

== Further reading ==
{{wikiquote}}
* [[Brinton, Willard Cope]]. ''[https://archive.org/details/graphicmethodsfo00brinrich Graphic methods for presenting facts]''. The Engineering magazine company, 1914.
* [[Karsten, Karl G.]] ''[http://catalog.hathitrust.org/Record/006593135 Charts and graphs: An introduction to graphic methods in the control and analysis of statistics].'' Prentice-Hall, 1923, 1925.

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[[Category:Infographics]]
[[Category:Diagrams|*]]
[[Category:Charts| ]]
[[Category:Modeling languages]]

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