two or more variables are measured to obtain a set of scores for each individual. examined to identify any patterns of relationship that exist between the variables and to measure the strength of the relationship

a list showing the two scores of each individual or the scores can be shown in a graph

numerical value to measure and describe the relationship between two variables

correlation describes 3 characteristics of a relationship:

there is a tendency for two variables to change in the same direction; as one variable increases, the other also tends to increase

there is a tendency for two variables to change in the opposite direction; increases in one variable tend to be accompanied by decreases in the other

when the data points in the scatter plot tend to cluster around a straight line

is used to describe and measure linear relationship when both variables are numerical scores from interval or ratio scales

a relationship that is consostently one-directional, either consistently positive or consistently negative

is used to measure a describe monotonic relationships when both variables are ranks from an ordinal score or have been transformed to ranks

is the squared value of a correlation and measures the percentage of variability on one variable that is determined, or predicted, by its relationship with the other variable

is the second important factor for interpreting the strength of a correlation

when a corelational study demonstrates a relationship between two variables, it allows researchers to use knowledge about one variable to help predict or explain the second variable

variable being explained or predicted

2 limitations in a Correlational study:

used for studying multivariate relationships