# [ncl-talk] regCoef(x,y)

Dennis Shea shea at ucar.edu
Mon Aug 1 10:13:59 MDT 2016

```If  q(nlat,mlon) and prob(nlat,mlon)  and the probabiliy units are percent
(%),

q = where ( prob.le.95,  q at _FillValue,  q)

NCL graphics ignore (ie, will not plot) wherever it encounters a _FillValue

http://www.ncl.ucar.edu/Document/Functions/Built-in/where.shtml

On Mon, Aug 1, 2016 at 9:23 AM, Xi Chang <xi.chang01 at gmail.com> wrote:

> Hi Dennis,
>
> So, is it correct if I plot like this:
>
> prob = (1.-*betainc*(df/(df+tval^2),df/2.0,b))*100.
>
> In the example that you pointed out, it is not really clear for me.
>
>
> Chang
>
>
> On Thu, Mar 17, 2016 at 9:32 PM, Dennis Shea <shea at ucar.edu> wrote:
>
>> See example 2  of
>>
>> http://www.ncl.ucar.edu/Document/Functions/Built-in/betainc.shtml
>>
>> ---
>> If you are testing at the 5% level (0.05) and prob is < 0.05, it is
>> significant.
>>
>>
>>
>> On Thu, Mar 17, 2016 at 2:10 PM, Xi Chang <xi.chang01 at gmail.com> wrote:
>>
>>> Hallo NCL,
>>>
>>> I looked at exampled 2
>>> <https://www.ncl.ucar.edu/Document/Functions/Built-in/regCoef-1.shtml>,
>>> which is exactly my case. But it's not clear after getting "prob" defined
>>> as :
>>>
>>> *prob= betainc*(df/(df+tval^2),df/2.0,b)
>>>
>>> How could I determine that only signals that are statistically
>>> significant at 95% will be shown in the plot.
>>>
>>> any help?
>>> Thanks
>>>
>>> Chang
>>>
>>>
>>>
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>>
>
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