About z-statistics and t-statistics (CFA Video)
About z-statistics and t-statistics (CFA Video)
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Q:
How to estimate the mean of a normally distributed population? (1,3,4,1,8,9)
A:
We can take n samples from the population. And we claim the mean of the sample
is the best estimation of the mean of the population.
For
n=2:
(1,3), (3,1), (8,9) …
Mean: (2), (2), (8.5) …
The
mean of the samples will be normally distributed also!
And the variance of the mean of the sample represents how confident you are with the sample mean.
Z-statistics
=
(x0-m0)/s_samplemean (1)
=
(x0-m0)/ (s_population/sqrt(n)) (2)
What
if s_population is unknown? The mean will following
t-distribution and just use equation (1) with t statistics
s_samplemean is standard error of sample mean. When variance of the population is unknown, use s_samplemean = s_sample/sqrt(n) instead of s_population/sqrt(n).
Sorry I didn’t further substitue s_samplemean = s_sample/sqrt(n) when mentioning t-statistics (equation 1).
Hi Editor:
Do you have videos for output and cost?
I am your paid customer.Please let me know.I was looking for videos for MC,MB ,AC etc.
Thanks,
Bharati
Hi Bharati,
Please include you email in the comment next time so that we can verify. If you are paid customer, yes, we put your request on the top of our list. Thanks!
Hi Bharati, We start doing output and cost now, here is the 1st one
http://minute-class.com/finance/marginal-total-and-average-products-cfa-video/