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Oct
18
comment Visualize a large binary matrix with instances and three classes
You can visualise an matrix for example using image but you might want to reorder the rows and columns first into clusters or something similar
Oct
18
comment How to quantify the importance of a win in soccer?
You would want to give it a rating similar to teams it was perceived to be as likely to win or lose against.
Oct
17
comment Why doesn't runif generate the same result every time?
Or xkcd
Oct
17
comment Why doesn't runif generate the same result every time?
@ssdecontrol: See Dilbert
Oct
15
comment Variance in significance with interaction term
First note that there is no major difference in substance between $-0.017$ and $-0.019$ even if the latter gets a . Second, the interaction term says that the $-0.019$ becomes $-0.033$ when *Rule of Law is $+1$ and $-0.047$ when Rule of Law is $+2$ but $+0.009$ when Rule of Law is $-2$. Finally remember that this is a model and the world is more complicated: historically the rule of law is in part the result of competing property owners find a dispute resolution procedure which does not involve violence.
Oct
15
comment Variance in significance with interaction term
What is wrong with "The effect of NatRent is now the effect of NatRent when Rule of Law is zero"?
Oct
12
comment Fewest weight possible of the balls
This is a puzzle, not a statistics question. You can find the odd ball of $4$ in $2$ weighings (a) if you do not need to know whether the odd ball is heavier or lighter or (b) if you have a fifth ball you know is of standard weight you can use.
Oct
10
comment Definition of Parameters
Don't parameters just take you from a general case or a family of cases to a particular one? So a Gaussian distribution with $\mu=10$ and $\sigma^2=4$ is a particular case of Gaussian distributions, in the same way that a straight line with gradient $10$ and intercept $4$ is a particular case of straight lines.
Oct
2
comment R code to solve for probability of normal distributions?
stat.ethz.ch/R-manual/R-devel/library/stats/html/Normal.html
Oct
2
comment R code to solve for probability of normal distributions?
Try ?pnormand ?qnorm
Oct
2
comment How can I work out the standard deviation of a t-distribution?
Do you mean $\frac{\nu}{\nu-2}$ for $\nu \gt 2$?
Oct
2
comment What does O(t) correction mean?
en.wikipedia.org/wiki/Big_O_notation
Oct
1
comment Help! Stat test to compare groups
Even if you are able to distinguish the two countries, but remember that correlation is not causation (the "because of" in your hypothesis).
Sep
26
comment How to turn my data into a ROC curve in R?
So if you use one of the packages and ask the right way, it is all done for you
Sep
20
comment Numbers too large for R. How to approximate probability mass function?
+1. For an example using logs, see the code in the question math.stackexchange.com/questions/465318/… which calculates $\displaystyle\sum_{i=0}^n (-2)^i {n \choose i}\frac{(2n-i)!}{(2n)!}$ for $n= 10^6$
Sep
15
comment If I divide my data by its mean, does it still have a unit?
Unitless$\displaystyle$
Sep
15
comment Covariance of $cov(5W_7+6W_9,W_7)$ where $W_t$ is a standard Brownian motion
@Glen_b: Thank you for spotting that
Sep
14
comment Covariance of $cov(5W_7+6W_9,W_7)$ where $W_t$ is a standard Brownian motion
Your title says $cov(5W_7+6W_9,W_3)$ but your calculations use $cov(5W_7+6W_9,W_7)$.
Sep
6
comment Do mean, variance and median exist for a continuous random variable with continuous PDF over the real axis and a well defined CDF?
As for the median, you could say that the median is a closed interval, and in many examples that interval reduces to a single point.
Sep
6
comment Do mean, variance and median exist for a continuous random variable with continuous PDF over the real axis and a well defined CDF?
I would say that the second moment of a Cauchy random variable is infinite, but that its variance is not defined (since it depends on the undefined mean).