# Question about normalization before estimate the spectrum

I work with a Electrophysiologist Team and i have seen something who interrogate me (i'm a noobs in DSP).

They acquires a signal into a brain structure (an LFP to be precise) :

• in a first time they apply a zscore(standard score) normalization on the raw data

• then they computes a spectral estimation with a CWT(continuous wavelet transform, morlet in this case)

Is that not a bias to use a normalization like a zscore before estimate the spectrum(or to do anything else in DSP)? Or is that a common way to deal?

Thank you for a potential answer.

Nicolas

$$x' = \frac{x-a}{b}$$
of which the $z$-score is a special case. The potential bias can easily be inverted.
• With my shallow knowledge about the brain: sensors response amplitudes can vary a lot with coupling, location, stimulus. So, if you want to combine, filter, separate sources from several different sensors, normalization is convenient. Whether the $z$-score is the best, most robust, etc. remains an open question (to me) – Laurent Duval Feb 11 '18 at 19:19