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statistics
Message posted by richie robles (via 203.177.18.182) on August 11, 2001 at 9:44 PM (ET)
what is z-test and t-test?
give an example of z-test and t-test?
what are the statistics tools?
this is my self research!!!
pls help me...
READERS RESPOND:
(In chronological order. Most recent at the bottom.)
Re: statistics
Message posted by Wizard of Odds (via 216.175.115.57) on August 12, 2001 at 2:38 AM (ET)
Actually this is basic stuff if you thought to buy a textbook and read about sampling.Small samples from a normal distribution have averages that follow the t-distribution (e.g. n<30). Larger samples follow a normal distribution and we generally us the z-table to find probabilities related to sample means.
Re: statistics
Message posted by JG (via 128.8.22.170) on August 12, 2001 at 6:59 PM (ET)
If X has a normal distribution, then Z=(X-mean(X))/S.D.(X) has a Z distribution where mean(Z)=0 and SD(Z)=1 . If SD(X) is estimated then Z becomes t , where t and Z are similar for n>30 and almost identical for n>120.
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