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seen Aug 19 at 0:22

Jul
19
awarded  Yearling
Jul
2
awarded  Curious
Apr
4
awarded  Custodian
Apr
4
reviewed No Action Needed Linear Inequalities - Allocation Problem
Apr
4
comment Normal Distribution - Statistics
@ScottGoddard Join ##statistics (or ##math, I'm on both) on irc.freenode.net, stackexchange isn't meant for lengthy discussions.
Apr
4
comment How do we square a random variable?
I think you might have gotten integration limits or similar wrong (nothing you shouldn't be able to fix by just rereading what you did, could also just be me who's handicappted at computation :)), otherwise it looks reasonable.
Apr
4
comment Normal Distribution - Statistics
Note that one has to impose some requirements on the distribution you're taking averages of the observations of (which basically make sure that taking averages makes any sense to begin with, check wikipedia for details).
Apr
4
comment Normal Distribution - Statistics
@ScottGoddard Getting into details about CLT gets kind of technical, esp. once you get to its generalisations. For the common case replace "averaging operations" by "sample mean of independent variables" (say, the average of multiple independent measurements of some fixed quantity to reduce instrument noise). If you do this multiple times for different sets of independent observations, you get multiple such "averages", the CLT now states that as the number of observations in each sample gets large, the collections of averages look more and more like being taken from a normal distribution.
Apr
4
comment Normal Distribution - Statistics
Is this a jeopardy question, where we're to figure out the question given the answers :)? Also, the central limit theorem does not imply that any sample can be approximated by a normal distribution (which I guess is supposed to mean that the empirical distribution of a sample is approximately normal), it merely states that certain kinds of averaging operations yield (asymptotically) normally distributed things, when applied to sufficiently well behaved distributions.
Apr
4
comment How do we square a random variable?
Have you tried taking the derivative of $F(t)=P(Y<t)=P(X^2<t)=P(-\sqrt t<X<\sqrt t)$?
Mar
9
comment Is P finitely additive when P(A) = 0 if A is Finite?
Take a couple of disjoint infinite subsets, say A, and B, then their union is still just an infinite set (thus of measure 1), but what about the sum of their individual measures?
Feb
28
awarded  Necromancer
Jan
7
accepted Software for organising mathematics
Jan
7
comment Software for organising mathematics
This seems similar to using Emacs Org-mode, which is/was my as of yet unimplemented plan. Nice overview with motivating examples! Is there any reason for stressing Windows-based?
Jul
19
awarded  Yearling
Aug
22
revised Specifying morphisms of slice categories fibrewise.
edited body
Aug
22
comment Specifying morphisms of slice categories fibrewise.
Very nice writeup, thanks! I figured the statement couldn't be true (in general). Now I just need to figure out what they mean by fibrewise :)
Aug
22
accepted Specifying morphisms of slice categories fibrewise.
Aug
22
asked Specifying morphisms of slice categories fibrewise.
Jul
25
comment How to define an action of an algebra on a set?
As far as I can see you need additional operations on the collection of endomorphisms of your sets. So perhaps if you passed from Sets to some enriched category? I can't say I can think of any interesting example of such a structure though, and it seems quite asymmetric. I'm wondering if the notion of a group action shouldn't be considered more of a construction on sets than on groups, arising due to the existence of a canonical group structure on the set of automorphisms of a set (or more generally the objects of a category).