Sharp EL-5100 Instruction Manual page 55

equals —1 or 1, all points on the correlation diagram are on a line. The further the value of r is from
—1 and 1, the less the points are massing about the line and the less reliable is the correlation. If r is more
than 0, it shows a positive correlation (Y is in proportion to X ) and if r is less than 0, it is a negative
correlation (Y is in inverse proportion to X).
The equation for the straight line is Y = a + bX. The point at which the line crosses the Y axis is a. The slope
is b.
r
a
b
Correlation coefficient
$xy
r =
Vs.
' xx ' ^yy
a =
y —
bx
Coefficient of linear
regression equation Y = a + bx
§xx
Syy = S /
s
x y = Z x y
\
( S x ) 2 >
n
( X y ) 2
n
X x -Xy
n
)
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