Thinning hair

Concerning thinning hair, would it be accurate to say that something like decrease in hair density (without miniaturization) might be temporary and stress-induced, but evidence of miniaturization would almost certainly be MPB? Is miniaturization obvious from hair diameter or does it require magnification?

Hair grows in groups called Follicular units which contain between 1-5 hairs each along with one or two vellus hairs. With age or genetic balding, the hair count within these groups can be reduced making a person’s hair look thinner (less full).