Statistics 7: The Correlation Coefficient

correlation coefficient

descriptive statistic that summarizes and describes the important characteristics of a relationship: type + strength

scatterplot

a graph that shows the location of each data point formed by a pair of X-Y scores

outlier

a data point that is relatively far from the majority of data points in the scatterplot. An extreme score which may bias your computations

type of relationship

- the overall direction in which the Y scores change as the X scores change

linear relationship

- forms a pattern that follows one straight line
- as X scores increase, Y scores tend to change in only one direction (increase if positive, decrease if negative)

regression line

the line on a graph that summarizes a relationship, by passing through the center of a scatterplot

nonlinear/curvilinear relationship

As the X scores change, the Y scores do not tend to only increase or only decrease - at some point the Y scores change their direction

strength of relationship

the extent to which one value of Y is consistently paired with one and only one value of X

Pearson correlation coefficient (r)

describes the type (either positive and negative) and the strength of the linear relationship between two interval and/or ratio variables

Spearman rank-order correlation coefficient (rs)

describes the linear relationship between two variables when measured by ranked (ordinal) scores

correlation coefficient

descriptive statistic that summarizes and describes the important characteristics of a relationship: type + strength

scatterplot

a graph that shows the location of each data point formed by a pair of X-Y scores

outlier

a data point that is relatively far from the majority of data points in the scatterplot. An extreme score which may bias your computations

type of relationship

- the overall direction in which the Y scores change as the X scores change

linear relationship

- forms a pattern that follows one straight line
- as X scores increase, Y scores tend to change in only one direction (increase if positive, decrease if negative)

regression line

the line on a graph that summarizes a relationship, by passing through the center of a scatterplot

nonlinear/curvilinear relationship

As the X scores change, the Y scores do not tend to only increase or only decrease - at some point the Y scores change their direction

strength of relationship

the extent to which one value of Y is consistently paired with one and only one value of X

Pearson correlation coefficient (r)

describes the type (either positive and negative) and the strength of the linear relationship between two interval and/or ratio variables

Spearman rank-order correlation coefficient (rs)

describes the linear relationship between two variables when measured by ranked (ordinal) scores