Question

Can A Probability Density Ever Be Negative?

Answer 1

A probability function gives a probability, so it cannot be greater than one.

A probability density function $f\left(x\right)$, however, may give a value greater than one for some values of $x$, since it is not the value of $f\left(x\right)$but the area under the curve that represents probability.

Hence, probability density cannot be negative.