The discussion centers around the notations used in probability, specifically the meanings of X and x in the probability density function notation f_{X}(x). Participants explore the definitions and implications of these symbols within the context of probability theory.
Participants express differing views on the flexibility of the notation's meaning, with some asserting a standard interpretation while others suggest variability based on the author's intent. The discussion remains unresolved regarding the extent of standardization in notation.
Some assumptions about the familiarity with probability notation and the context of its use may be missing. The discussion does not resolve the potential ambiguity in notation across different contexts.
dexterdev said:Hi all,
I would like to make things clear about the notations used in probability. what does X and x in pdf
f[itex]_{X}[/itex](x) means.
-Devanand T
The uppercase X designates the random variable. The lowercase x designates some particular value of the random variable.dexterdev said:Hi all,
I would like to make things clear about the notations used in probability. what does X and x in pdf
f[itex]_{X}[/itex](x) means.
No, it doesn't mean "whatever the person who wrote it decides that it means", and it's best not to guess when you don't know the answer. Suppose you're reading up on chemistry and you come across H2O. This doesn't mean whatever the author intended. It has a very specific meaning. It's water. Similarly, the nomenclature [itex]f_X(x)[/itex] is widely used to mean the probability density function or probability mass function for some random variable [itex]X[/itex]. That nomenclature is standard, just as is H2O.ImaLooser said:Well, it means whatever the person who wrote it decides that it means. I would guess that fX() is a random function, and x is some sort of value. Like fX(x) could be equal to x + X.