AP Stats Chapter 3 Vocab
scatter plot
a graph which shows the relationship between two quantitative variables measured on the same individual
residual plot
a scatterplot of the residuals against the explanatory variable x; helps assess how well a regression line fits the data
regression line
a straight line that describes how a response variable ychanges as an explanatory variable xchanges
y-intercept
a; the predicted value of y when x = 0
outlier
an observation that lies outside the overall pattern of the other observations
slope
b; the rate at which the predicted response (y hat) changes along the line as the explanatory variable x changes
standard deviation of the residuals
gives the approximate size of a typical or average prediction error (residual)
negative association
high values of one variable tend to occur with low values of the other variable
positive association
higher values of the two variables tend to occur together
residual
the differences between the observed and the predicted values of y; equals observed y minus predicted y
least-squares regression line
the line that makes the sum of the squared residuals as small as possible
equation of the least squares regression line
the straight line y hat = a +bx; that minimizes the sum of the squares of the vertical distances of the observed points from the line
coefficient of determination
r squared; the fraction of the variation in the values of y that is accounted for by the least-squares regression line of y and x
influential observation
individual points that substantially change the correlation or the regression line
explanatory variable
may help explain or influence changes in a response variable
variation
the average squared distance
response variable
measures an outcome of a study
correlation
measures the strength and direction of the linear association between two quantitative variables x and y