Confidence region overlaps the pole. Confidence limits for Amplitude and Acrophase cannot be determined. (CICalc in Cosinor)

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Hi, can someone explain to me why this message appears in the CICalc function from the Cosinor analysis?
The message says: " Confidence region overlaps the pole. Confidence limits for Amplitude and Acrophase cannot be determined".
I would like to know:
  1. Why the confidence region overlaps the pole?
  2. Why the confidence limits cannot be determined?
  3. What can I do for this not happen?
Thanks

回答(1 个)

Star Strider
Star Strider 2016-6-6
Well, ‘pole’ is new to me, and apparently also to The Dictionary of Circadian Physiology. A PubMed search for it points me to circadian rhythm studies in the high Arctic. Probably not the sort of ‘pole’ you’re interested in.
My guess is that ‘pole’ refers to the centre of the plot. If that’s correct, it would mean the same as the confidence limits including zero, therefore the estimated parameters are not significant, and no circadian rhythm exists for the variable you’re studying.
You might want to email the author of those functions to clarify this.
My only other suggestion is to see if you can fit your data using Curve fitting to a sinusoidal function, but using the Statistics (and Machine Learning) Toolbox function nlinfit and nlparci in addition to (that is, after) the fminsearch call I used. Use the parameter estimates from fminsearch as the initial parameter estimates for nlinfit.
I don’t have your data to experiment with, but it’s worth a go to see if you can get an acceptable fit and parameter estimates. You can then use the cart2pol function to plot it as a characteristic polar plot.
  6 个评论
Kelvin Prado
Kelvin Prado 2016-6-7
编辑:Kelvin Prado 2016-6-7
Thanks for the tips, if I succeed in improving the Cosinor function in any way, I certainly will share it in the File Exchange. I really think we can all work together to write better codes and make our life easier.
Star Strider
Star Strider 2016-6-7
My pleasure.
My only attempt prompted the routine I quoted. It worked for my data. (I altered it slightly to provide a relevant Answer to that Question.)

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