Bivariate Data

negative correlation (association)

a relationship between two variables such that as the value of one variable increases, the other decreases.

correlation

a statistical measure that indicates the extent to which two factors vary together and thus how well one factor can be predicted from the other. Correlations can be positive or negative.

nonlinear correlation

any correlation in which the rates of change of the variables is not constant.

positive correlation (association)

as one set of values increases, the other set tends to increase

residual

calculated by using actual data - predicted data

correlation coefficient

a number "r" from -1 to 1 that measures the strength and direction of the correlation of two variables.

scatterplot

A graphed cluster of dots, each of which represents the values of two variables.

linear regression

A statistical technique that determines the best fit line to a set of data to allow prediction of the score on one variable from the score on another variable

outlier

A value much greater or much less than the others in a data set

linear association

Data points that do not form a straight line. An association between two variables that would, if represented in a scatter plot, conform to a general pattern of a straight line

bivariate data

Data with two variables, or pairs of numerical observations.

Response Variable

The outcome variable, also known as a dependent variable (as y-axis)

no correlation ( association)

There is no relationship between data sets.

explanatory variable

Variable that is used to explain variability in the response variable, also known as an independent variable or predictor variable (as x-axis )

residual plot

a graph that shows the residuals on the vertical axis and the independent variable on the horizontal axis

coefficient of determination

denoted "R squared", is the proportion of the variance in the dependent variable that is predictable from the independent variable(s) (the linear regression prediction accuracy or confidence)

line of best fit

the most accurate trend line on a scatter plot showing the relationship between two sets of data