It is two-tailed t-test. It is not obvious but 'ttest'
uses the incomplete beta function (betainc) to calculate
the probability.
See Example 2 at
http://www.ncl.ucar.edu/Document/Functions/Built-in/betainc.shtml
This illustrates how to get the one-tailed probability.
There is also a link where you can get the one and two tailed
probabilities.
Good luck
On 8/1/11 1:53 PM, Nicole Schiffer wrote:
> Does anyone know if the NCL ttest function performs a one- or two-tail
> t-test? If it is two-tail, the critical level of significance is split
> between the tails, correct?
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Received on Mon Aug 1 14:55:40 2011
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