n n i=1 (x1i − x1)(x2i − x2) x1, x2の共分散 + + + + + + + x1 x2 x2 x1 < 0 < 0 > 0 > 0 ( x 1 i – x 1 ) ( x 2 i – x 2 ) ( x 1 i – x 1 ) ( x 2 i – x 2 ) ( x 1 i – x 1 ) ( x 2 i – x 2 ) ( x 1 i – x 1 ) ( x 2 i – x 2 )
n n i=1 (x1i − x1)(x2i − x2) x1, x2の共分散 + + + + + + + x1 x2 x2 x1 < 0 < 0 > 0 > 0 ( x 1 i – x 1 ) ( x 2 i – x 2 ) ( x 1 i – x 1 ) ( x 2 i – x 2 ) ( x 1 i – x 1 ) ( x 2 i – x 2 ) ( x 1 i – x 1 ) ( x 2 i – x 2 ) 共分散の正負 = 相関の正負
n n i=1 (x1i − x1)(x2i − x2) x1, x2の共分散 + + + + + + + x1 x2 x2 x1 < 0 < 0 > 0 > 0 ( x 1 i – x 1 ) ( x 2 i – x 2 ) ( x 1 i – x 1 ) ( x 2 i – x 2 ) ( x 1 i – x 1 ) ( x 2 i – x 2 ) ( x 1 i – x 1 ) ( x 2 i – x 2 ) 共分散の正負 = 相関の正負 (共分散を x1, x2 の標準偏差で 割ったものが相関係数)