A scatter plot is a set of points plotted on a horizontal and vertical axes.

Scatter plots are important in statistics because they can show the extent of correlation, if any, between the values of observed quantities or phenomena (called variables). If no correlation exists between the variables, the points appear randomly scattered on the coordinate plane. If a large correlation exists, the points concentrate near a straight line. Scatter plots are useful data visualization tools for illustrating a trend. 

Besides showing the extent of correlation, a scatter plot shows the sense of the correlation:

  • If the vertical (or y-axis) variable increases as the horizontal (or x-axis) variable increases, the correlation is positive.
  • If the y-axis variable decreases as the x-axis variable increases or vice-versa, the correlation is negative.
  • If it is impossible to establish either of the above criteria, then the correlation is zero.

The maximum possible positive correlation is +1 or +100%, when all the points in a scatter plot lie exactly along a straight line with a positive slope. The maximum possible negative correlation is -1 or -100%, in which case all the points lie exactly along a straight line with a negative slope.

Correlation is often confused with causation, either accidentally (as a result of false or unproved hypotheses) or deliberately (with intent to deceive). However, in the pure sense, while a scatter plot can reveal the nature and extent of correlation, it says nothing about causation.

This video from RodCastMath explains more about negative and positive correlation on a scatter plot.

See also: graph theory, pictograph, bar graph, point-to-point graph, sparkline, time series chart

This was last updated in December 2012
Contributor(s): Stan Gibilisco
Posted by: Margaret Rouse

Related Terms

Definitions

  • semi-structured data

    - Semi-structured data is data that has not been organized into a specialized format, such as a table, a record, an array or a tree but that nevertheless has associated information, such as metadata,... (WhatIs.com)

  • clinical decision support system (CDSS)

    - A CDSS, or clinical decision support system, is data analysis software or an application that care providers reference during treatment. (SearchHealthIT.com)

  • recommendation engine

    - Recommendation engines are common among online retail websites, such as Amazon. Also known as recommender systems, these applications suggest products (or something else a visitor might search for,... (WhatIs.com)

Glossaries

  • Business intelligence - business analytics

    - Terms related to business intelligence, including definitions about business analytics and words and phrases about gathering, storing, analyzing and providing access to business data.

  • Internet applications

    - This WhatIs.com glossary contains terms related to Internet applications, including definitions about Software as a Service (SaaS) delivery models and words and phrases about web sites, e-commerce ...

Ask a Question. Find an Answer.Powered by ITKnowledgeExchange.com

Ask An IT Question

Get answers from your peers on your most technical challenges

Ask Question

Tech TalkComment

Share
Comments

    Results

    Contribute to the conversation

    All fields are required. Comments will appear at the bottom of the article.