Re: bell shaped distribution


exciter wrote:
Hello people,

I was wondering the definition of "distribution".
Well in the first place this may seem an easy question but sometimes
this word is used in many ways. For instance the evolution of a
variable through time can be called distribtuion (through time.
However, a bell shaped curve is also called a distribtuion.
Then I wonder to what we call a distrubtion?
Shall we briefly discuss this?
Regards,
Exciter

A (continuous) distribution, or pdf (probability density function) is
a function f(x) which has these TWO properties: (a) It is everywhere
non-negative and (b) the integral from -inf to + inf. (or areas under
the curve) is 1. The distribution describes the behaviour of the
random variable X associated with it.

A "bell-shaped" distribution is arguably the WORSE description
anyone can give to identify a pdf, because the majority of the
well-known pdf's are bell-shaped: Normal, T (1 to infinite
degress of freedom), chi-squared (for large d.f.), and even
certain beta distribution defined on (0,1).

Simply identify a pdf by its two properties -- regardless of its shape,
and by the known properties of certain classes of distributions
having those shapes.

-- Bob.

.

Relevant Pages