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How do you interpret r value?
There is a (w, m, s), (pos, neg), linear relationship between x and y
what is a weak correlation?
less than 0.5
what is a moderate correlation?
0.5 to 0.8
what is a strong correlation?
0.8 to 1
what is a residual?
actual - predicted
extrapolation
using model to make predictions outside range of data
Slope interpretation
On average, for every increase in one x, we predict the y to (inc, dec) by slope units
Y-int interpretation
When x variable is 0, we predict the y variable to be y-int
what point will the LSRL always go through?
x bar, y bar
how can you find b?
b = r(Sy / Sx)
all influential points are outliers…
but NOT all outliers are influential
what is an example of an outlier that is not influential?
an outlier in the same direction of the trend
When a residual plot has a pattern…
a linear model will be a BAD fit
coefficient of determination
R²
percent variation in the y can be explained by linear relationship between y and x
R² formula
R² = 1 - (SSResid / SSTotal)
Se
measures a typical amount of variability in the vertical distances from the y to the regression line
Note 
Flashcard (111)