# Normal Distribution Quick Q

1. ### zmike

103
I am a bit confused with the notation, Whenever I see N(mu,alpha) does that mean the data set is normal and does it also mean that it's standard normal?

Is there a difference between using Z~N(mu,alpha) vs. X~N(mu,alpha)? does the Z indicate standard normal?, if so why don't we just use Z(mu,alpha)?

Can I still use this notation N(_,_) when the data set is NOT normal?

Last edited: Oct 18, 2010
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3. ### mathman

6,576
Standard notation: X~N(m,d) means X is a random variable, with a normal distribution having a mean m and standard deviation d. If you wrote Z(m,d) then you need to define Z. N(m,d) means the distribution is normal - you can't use it for something else - it is a matter of notation.

If d is unknown for a normal distribution with a known m, then, as you observed, you can specify the midpoint of the distribution, but nothing else.