AP STAT REVIEW: Other

Describe Scatter Plot

Describe Scatter Plot

Form, direction, strength, outliers, unusual patterns, context

r

-1 to 1, tells strength and direction of relationship, closer to zero = weaker

r^2

0 to 1, tells how good of a job the model does, the % of the variation in y that is explained by the variation in x, higher = good

S

Standard deviation of residuals, typical error of predicted y-values from the observed y-values.

Heteroskedasicity

variation of the variance

Slope

for every one unit increase in [X-VAR] there is predicted [SLOPE] inc/dec in [Y-VAR]

Slope Equation

b = (r) sy/sx

y-int equation

(y mean) - b(x mean)

Effect of adding or subtracting a constant

adds/subtracts a from mean/median/quartiles/percentiles, does not change distribution shape or range/IQR/standard deviation

Effect of multiplying or dividing by a constant

multiplies/divides mean/median/quartiles/percentiles, by b, multiplies/divides range/IQR/std. dev., does nt change snape