Studied by 1 person
Explanatory Variable
attempts to explain the observed outcomes
Response variable
measures the outcome of the study
Scatterplot
shows the relationship between two quantitative variables measured on the same individuals
Form of a scatterplot
linear or curved
Direction of a scatterplot
is positive, negative, or neither
Strength of a scatterplot
is weak, moderate, or strong
Outlier
lies outside the overall pattern
Positively associated
as one increased the other increases
Negatively associated
as one increases the other decreases
Coorelation
mesures the strength and direction of the relationship between 2 quantitative variables; represented by r
Facts on correlation
r does not change if x and/or y are changed
positive r = positive association and negative r = negative association
always a number between -1 and +1
measures strength of a linear relationship
is nonresistant
regression line
describes how a response variable y changes as explanatory variable x changes; predicts values of y for given values of x
R-squared
percentage of the change in the y-variable that can be attributed to its relationship with the x-variable
Residual
difference between observed value of y and a value predicted by the regression line; residual = actual y - predicted y
Residual plot
scatter plot of each x-value and its residual value
Influential point
the removal of the point has a large effect on the correlation and / or regression
