[blackrock]

So, to put this in human terms.

A false positive or false negative, can be like a pregnancy test.

A false positive, can be where the pregnancy test shows your wife is pregnant, but she is not. And the baby never arrives. Phew, dodged a bullet!

A false negative, can be where the pregnancy test shows your wife is not pregnant, but she really is. And 9 months later, a baby accidentally pops out. Oh crap!

[joshuamorton]

Of course false-positives can also be bad. To use your example "you then spend $10,000 prepping for the baby, but it never comes, what a waste!"