# Trying to understand the lambda2 parameter in mne.minimum\_norm.apply\_inverse\_raw **URL:** \ **Category:** Support & Discussions\ **Tags:** source-localization, eeg\ **Created:** [April 20, 2023, 5:49am UTC](https://mne.discourse.group/t/trying-to-understand-the-lambda2-parameter-in-mne-minimum-norm-apply-inverse-raw/6764 "2023-04-20T05:49:31Z")\ **Posts on this page:** 1\ **Showing post:** 2
**Author:** ![richard](https://yyz2.discourse-cdn.com/free1/user_avatar/mne.discourse.group/richard/32/15_2.png) [@richard](https://mne.discourse.group/u/richard)\ **Post date:** [April 20, 2023, 7:31am UTC](https://mne.discourse.group/t/trying-to-understand-the-lambda2-parameter-in-mne-minimum-norm-apply-inverse-raw/6764/2 "2023-04-20T07:31:47Z")
Hello! This is a recurring question, and the answer – albeit maybe unsatisfactory to you – is that you should simply assume an SNR of 3 for averaged and 1 for non-averaged data: > [@Estimating the regularization parameter for HCP MEG resting state source reconstruction](https://mne.discourse.group/t/estimating-the-regularization-parameter-for-hcp-meg-resting-state-source-reconstruction/5177/15): > > @Dominik I just asked @agramfort about this while we were fighting with the coffee machine (spoiler: we won! muscle coffee) He said this parameter (SNR of 3 for averaged, 1 for non-averaged data) “was established by Matti Hämäläinen 20 years ago”, and that “no one touches this parameter”. Hence … I would say, case closed. wink Best wishes, Richard Best wishes, Richard --- _[View the full topic](https://mne.discourse.group/t/trying-to-understand-the-lambda2-parameter-in-mne-minimum-norm-apply-inverse-raw/6764)._