Qualification > Math

Statistics II Question

<< < (2/3) > >>

astarmathsandphysics:
I just want to remind you that for a poisson distribution the mean is equal to the variance so to find the variance, find the mean first

vince_24:
Okay, yes. The original Variance is just npq.

When Y is doubled, why is the new variance 2^2 * 5 * 0.5(1-0.5) ? I don't understand the 2^2 bit. Why is it not just 2? Why are some questions 2^2 and some just 2?

astarmathsandphysics:
V=sum(x-m)^2/(n-1) so if all the x's are doubled
V=sum(2x-2m)^2/(n-1)=V=2^2sum(x-m)^2/(n-1)

astarmathsandphysics:
mean =sumx/n if the x's are doubled then mean=sum(2x)/n=2sumx/n so the mean is doubled

vince_24:

--- Quote from: astarmathsandphysics on November 08, 2009, 07:38:49 am ---mean =sumx/n if the x's are doubled then mean=sum(2x)/n=2sumx/n so the mean is doubled

--- End quote ---

Yeah, but I am confused with the variance part.

Navigation

[0] Message Index

[#] Next page

[*] Previous page