Is the linear regression slope always positive?

Question

In the context of this lesson, is the linear regression slope always positive?

Answer

Nope! The slope of a linear regression plot can be positive, negative, 0, or close to infinity.

With linear regression, the line plotted will always be a straight line, and have any valid slope value. However, because it is a straight line, it may not be the best model for certain datasets. For instance, some datasets might form a logarithmic curve, or even strictly have values that fall on either 0 or 1 for every data point. So even though any slope is possible, it is constrained by the linearity.

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The slope of a straight line is constant throughout. Then, how can you say the line plotted can have any slope value? Is it in context of valid value or something else? Please clarify my doubt.
Thanks.

Perhaps you’re misinterpreting slope here- https://en.wikipedia.org/wiki/Slope You could have a long, straight road but it can still have a slope. Constant does not imply zero.