Different notation $dP(x)$ and $P(dx)$












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Quick question that has been bugging me for a while: I have come across both the notation $dP(x)$ as well as $P(dx)$ when looking at the $mathbb E[X]$ where $X$ is a continuous real random variable. Am I missing an important concept as to why both are used, rather than just one? Or are these notations simply equivalent?










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  • $begingroup$
    Neither of them means anything in their own except that the integral is with respect to the measure $P.$ In fact, you can drop the "$dx$" symbols everywhere and simply write $mathbf{E}(X) = intlimits_Omega X dP.$
    $endgroup$
    – Will M.
    Jan 29 at 20:27










  • $begingroup$
    They come handy when you have a function of two variables, say $x in Omega$ and $t in mathrm{T}$ and the measure $P$ is on $Omega.$ But even then the fact that $P$ is defined on $Omega$ should suffice...
    $endgroup$
    – Will M.
    Jan 29 at 20:28
















1












$begingroup$


Quick question that has been bugging me for a while: I have come across both the notation $dP(x)$ as well as $P(dx)$ when looking at the $mathbb E[X]$ where $X$ is a continuous real random variable. Am I missing an important concept as to why both are used, rather than just one? Or are these notations simply equivalent?










share|cite|improve this question









$endgroup$












  • $begingroup$
    Neither of them means anything in their own except that the integral is with respect to the measure $P.$ In fact, you can drop the "$dx$" symbols everywhere and simply write $mathbf{E}(X) = intlimits_Omega X dP.$
    $endgroup$
    – Will M.
    Jan 29 at 20:27










  • $begingroup$
    They come handy when you have a function of two variables, say $x in Omega$ and $t in mathrm{T}$ and the measure $P$ is on $Omega.$ But even then the fact that $P$ is defined on $Omega$ should suffice...
    $endgroup$
    – Will M.
    Jan 29 at 20:28














1












1








1


1



$begingroup$


Quick question that has been bugging me for a while: I have come across both the notation $dP(x)$ as well as $P(dx)$ when looking at the $mathbb E[X]$ where $X$ is a continuous real random variable. Am I missing an important concept as to why both are used, rather than just one? Or are these notations simply equivalent?










share|cite|improve this question









$endgroup$




Quick question that has been bugging me for a while: I have come across both the notation $dP(x)$ as well as $P(dx)$ when looking at the $mathbb E[X]$ where $X$ is a continuous real random variable. Am I missing an important concept as to why both are used, rather than just one? Or are these notations simply equivalent?







probability probability-theory measure-theory random-variables






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share|cite|improve this question











share|cite|improve this question




share|cite|improve this question










asked Jan 29 at 17:48









SABOYSABOY

592311




592311












  • $begingroup$
    Neither of them means anything in their own except that the integral is with respect to the measure $P.$ In fact, you can drop the "$dx$" symbols everywhere and simply write $mathbf{E}(X) = intlimits_Omega X dP.$
    $endgroup$
    – Will M.
    Jan 29 at 20:27










  • $begingroup$
    They come handy when you have a function of two variables, say $x in Omega$ and $t in mathrm{T}$ and the measure $P$ is on $Omega.$ But even then the fact that $P$ is defined on $Omega$ should suffice...
    $endgroup$
    – Will M.
    Jan 29 at 20:28


















  • $begingroup$
    Neither of them means anything in their own except that the integral is with respect to the measure $P.$ In fact, you can drop the "$dx$" symbols everywhere and simply write $mathbf{E}(X) = intlimits_Omega X dP.$
    $endgroup$
    – Will M.
    Jan 29 at 20:27










  • $begingroup$
    They come handy when you have a function of two variables, say $x in Omega$ and $t in mathrm{T}$ and the measure $P$ is on $Omega.$ But even then the fact that $P$ is defined on $Omega$ should suffice...
    $endgroup$
    – Will M.
    Jan 29 at 20:28
















$begingroup$
Neither of them means anything in their own except that the integral is with respect to the measure $P.$ In fact, you can drop the "$dx$" symbols everywhere and simply write $mathbf{E}(X) = intlimits_Omega X dP.$
$endgroup$
– Will M.
Jan 29 at 20:27




$begingroup$
Neither of them means anything in their own except that the integral is with respect to the measure $P.$ In fact, you can drop the "$dx$" symbols everywhere and simply write $mathbf{E}(X) = intlimits_Omega X dP.$
$endgroup$
– Will M.
Jan 29 at 20:27












$begingroup$
They come handy when you have a function of two variables, say $x in Omega$ and $t in mathrm{T}$ and the measure $P$ is on $Omega.$ But even then the fact that $P$ is defined on $Omega$ should suffice...
$endgroup$
– Will M.
Jan 29 at 20:28




$begingroup$
They come handy when you have a function of two variables, say $x in Omega$ and $t in mathrm{T}$ and the measure $P$ is on $Omega.$ But even then the fact that $P$ is defined on $Omega$ should suffice...
$endgroup$
– Will M.
Jan 29 at 20:28










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