# Statistics and Probability Dictionary

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### Slope

The **slope** of a line is a measure of
the "steepness" of the line.
On a
Cartesian plane, the slope of a line can be
computed from any two points on the line.

Slope =
( y_{1} - y_{2} ) /
( x_{1} - x_{2} )

where x_{1} and y_{1}
are the x and y coordinates for the first point; and
where x_{2} and y_{2}
are the x and y coordinates for the second point.

A positive slope is indicated by a line that goes up as you move from left to right along the X axis. A negative slope is indicated by a line that goes down as you move from left to right. And when the line is horizontal, the slope is zero. A line with zero slope is parallel to the X axis.

In the figure above, the green line has a positive slope; the blue line, a negative slope; and the red line, zero slope.

In the equation for a straight line, shown below, slope is one of the key parameters:

y = mx + b

where m is the slope of the line,
b is the
y intercept of the line, x is the independent variable,
and y is the dependent variable.