# LCMV Beamformer Regularization Parameter Does Not Affect Results

**URL:** <https://mne.discourse.group/t/lcmv-beamformer-regularization-parameter-does-not-affect-results/11842>\
**Category:** Support & Discussions\
**Tags:** source-localization\
**Created:** [May 26, 2026, 8:15pm UTC](https://mne.discourse.group/t/lcmv-beamformer-regularization-parameter-does-not-affect-results/11842 "2026-05-26T20:15:27Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![tzcheng911](https://yyz2.discourse-cdn.com/free1/user_avatar/mne.discourse.group/tzcheng911/32/3565_2.png) [@tzcheng911](https://mne.discourse.group/u/tzcheng911)\
**Post date:** [May 26, 2026, 8:15pm UTC](https://mne.discourse.group/t/lcmv-beamformer-regularization-parameter-does-not-affect-results/11842/1 "2026-05-26T20:15:28Z")

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MNE version: 1.11.0

operating system: Ubuntu 18.04

Dear beamformer experts,

I am experimenting with parameters in `mne.beamformer.make_lcmv`. Some parameter changes affect the source results as expected. However, I am confused about the regularization parameter (`reg`).

Specifically, changing `reg` (e.g., 0, 0.05, 0.1) does not seem to affect the source results at all, with all other parameters and input data are kept the same.

My question: Why might changing the regularization parameter have no apparent effect on the LCMV solution? Perhaps other parameters need to be set to have `reg` working, under what conditions would the `reg` parameter meaningfully influence the results?

I have included screenshots showing the results across different `reg` values and my code snippet calling the `mne.beamformer.make_lcmv`function for reference. Thank you very much.

Best,

Zoe

 ![image-4](https://global.discourse-cdn.com/free1/uploads/mne/original/2X/f/f9f16e701659edf8ab93582285118645a8ebe721.png)`filters = make_lcmv(evokeds_inv.info,`  
`fwd,`  
`data_cov,`  
`reg=0,`  
`noise_cov=noise_cov,`  
`pick_ori=“max-power”,`  
`weight_norm=“unit-noise-gain”,`  
`rank=‘info’,`  
`reduce_rank = True,`  
`depth = 0.8`  
`)`

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<div class="post-metadata">

**Author:** ![wmvanvliet](https://yyz2.discourse-cdn.com/free1/user_avatar/mne.discourse.group/wmvanvliet/32/100_2.png) [@wmvanvliet](https://mne.discourse.group/u/wmvanvliet)\
**Post date:** [May 29, 2026, 8:49am UTC](https://mne.discourse.group/t/lcmv-beamformer-regularization-parameter-does-not-affect-results/11842/2 "2026-05-29T08:49:37Z")

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my first guess would be a bug in your analysis code somewhere. Can you see what it inside the `filters` dictionary and confirm they change when you specify different values for `reg`? Also, how is the `data_cov` computed exactly? Did you apply any regularization there?

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<div class="post-metadata">

**Author:** ![tzcheng911](https://yyz2.discourse-cdn.com/free1/user_avatar/mne.discourse.group/tzcheng911/32/3565_2.png) [@tzcheng911](https://mne.discourse.group/u/tzcheng911)\
**Post date:** [June 12, 2026, 4:39am UTC](https://mne.discourse.group/t/lcmv-beamformer-regularization-parameter-does-not-affect-results/11842/3 "2026-06-12T04:39:54Z")

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> [@tzcheng911](#):
>
> Perhaps other parameters need to be set to have `reg` working

Hi Marijn,

Thanks for the reply. I looked into the `filters['data_cov']` and it does not seem to change regardless the value I entered for `reg`, with other parameters being the same as in the original post. Are there other parameters need to be set to have `reg` working?

To your question about how data\_cov was calculated: I used `mne.compute_covariance(data, tmin=0, tmax=0.15)` to compute data cov from the entire epoch. No regularization has been applied in that step.

Best,

Zoe