Re: Am I right with coherence probility

Well, you should read the two references.

I am not a statistician but I think you should use
the returned coherence and not sqrt(...)

Good luck

On 2/25/14, 2:46 PM, 朱学明 wrote:
> Hi Dennis,
> Thanks for your reply. Can you make sure for me which one is correct? Should I use sqrt or not?
>
> Am I rigth with the line
>> phase=where(sqrt(spec@coher).le.spec@coher_probability(1),phase@_FillValue,phase),
>> or
>> phase=where(spec@coher.le.spec@coher_probability(1),phase@_FillValue,phase)
>> in order to get the coherence satisfy the 95% confidence level?
>
>
> 2014-02-26
>
>
>
> Xueming Zhu 朱学明
> Key Laboratory of Research on Marine Hazards Forecasting (LoMF), SOA
> National Marine Environmental Forecasting Center (NMEFC)
> No.8, Dahuisi Road, Haidian District, Beijing, 100081
> People's Republic of China
> Tel:+86-10-82481923
>
>
>
> 发件人：Dennis Shea <shea@ucar.edu>
> 发送时间：2014-02-26 05:40
> 主题：Re: [ncl-talk] Am I right with coherence probility
> 收件人："朱学明"<557xiaozhu@163.com>,"ncl-talk@ucar.edu USERS"<ncl-talk@ucar.edu>
> 抄送：
>
> I would say "yes"
>
> On 2/24/14, 2:52 PM, 朱学明 wrote:
>> Sorry for the corrections.
>>
>>
>> Hello all,
>> I have two time series data and want to do cross spectrum analysis. Can you help me to check whether I have got the right coherence probility? My codes are as follow,
>>
>> fn = sec1+"_daily.dat.bak"
>> data = asciiread(fn,(/nline,2/),"float")
>> xn = data(:,1)
>> fn = sec2+"_daily.dat.bak"
>> yn = data(:,1)
>> wgtt = filwgts_lanczos (301,2,1/400,1/80,1.0)
>> XN = wgt_runave (xn,wgtt,0)
>> YN = wgt_runave (yn,wgtt,0)
>> delete([/xn,yn/])
>> xn = XN((nwgt-1)/2:(dimsizes(XN)-(nwgt-1)/2-1))
>> yn = YN((nwgt-1)/2:(dimsizes(YN)-(nwgt-1)/2-1))
>> spec = specxy_anal(xn,yn,0,5,0.1)
>> dataL=new((/2,dimsizes(spec@coher)/),typeof(spec@coher))
>> dataL(0,:)=sqrt(spec@coher)
>> dataL(1,:)=spec@coher_probability(1)
>> phase=spec@phase
>> phase@_FillValue= 1e20
>> phase=where(sqrt(spec@coher).le.spec@coher_probability(1),phase@_FillValue,phase)
>>
>> plot=gsn_csm_xy2(wks,spec@frq,dataL,phase,resL,resR); create plot
>>
>>
>>
>> Am I rigth with the line
>> phase=where(sqrt(spec@coher).le.spec@coher_probability(1),phase@_FillValue,phase),
>> or
>> phase=where(spec@coher.le.spec@coher_probability(1),phase@_FillValue,phase)
>> in order to get the coherence satisfy the 95% confidence level?
>>
>> Thanks.
>>
>> 2014-02-25
>>
>>
>>
>> Xueming Zhu 朱学明
>> Key Laboratory of Research on Marine Hazards Forecasting (LoMF), SOA
>> National Marine Environmental Forecasting Center (NMEFC)
>> No.8, Dahuisi Road, Haidian District, Beijing, 100081
>> People's Republic of China
>> Tel:+86-10-82481923
>>
>>
>>
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Received on Tue Feb 25 15:06:40 2014