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Correlations are a great tool for learning about how one thing changes with another. Correlation values closer to 0 are weaker correlations, while values closer to positive or negative 1 are stronger correlation. (Source)

In statistics, the Pearson correlation coefficient (PCC) ― also known as Pearson's r, the Pearson product-moment correlation coefficient (PPMCC), the bivariate correlation, or colloquially simply as the correlation coefficient ― is a measure of linear correlation between two sets of data.It is the ratio between the covariance of two variables and the product of their standard deviations; thus, it is essentially a normalized measurement of the covariance, such that the result always has a value between −1 and 1 (-1 ≤ r ≤ 1). (Source)

The "r value" is a common way to indicate a correlation value. More specifically, it refers to the (sample) Pearson correlation, or Pearson's r. The "sample" note is to emphasize that you can only claim the correlation for the data you have, and you must be cautious in making larger claims beyond your data. (Source)

Random Sample

An important type of Sample in Quantitative Research. When a Sample is chosen at random, it lessens the chance for any sort of systematic distortion of that Sample in relation to the Population.


The most primitive measure of Dispersion; it is the distance between the lowest score and the highest score.

Raw Data

Data that have been collected but not yet analyzed.


The part of an article where the published sources that were actually cited in the article are listed alphabetically.


A Statistical process where the values of a predictor Variable are used to help estimate the possible value of a target Variable.


A Statistical test used to measure the accuracy of the process used to gather Data. Some common forms of Reliability include test-retest reliability, alternate forms reliability, and internal consistency.

Repeated Measures

A Statistical Research Design used in Quantitative Research where Data is gathered from the same Participants at different times. A Pretest-Posttest design is a simple form of repeated measures.


The ability to repeat a research process and get the same answer. Most important in Quantitative Research.

Representative Sample

A type of Sample where some effort has been made to make sure the Sample resembles the Population in one or more important ways.

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