Formulate an answer on PhD defense about mistakes you've made Imagine, you did data evaluation, published. When preparing your data for the thesis, you've realized that your approach was wrong. It does not change the main course of the paper and do not damage main conclusions, although it does affect the quantitative part of research. It is more than 1 year back published, so instead of erratum you decided that you put your updated data in your thesis and will do your best to address your mistakes in the next publication.

Question is how to formulate decent answers during the PhD defense if the committee asks why didn't you publish erratum/correction if you've made a mistake in your data evaluation?

Could I answer in a way "I've realized I've made a mistake and it will not happen again. The correction will not change main conclusions of the publication. I will make sure to address these points in the next publication concerning this topic to avoid any misunderstanding"

Maybe some other ideas?

Thanks in advance!
If I were on your committee, the key take-away I would look for is that the mistake will be corrected in the literature.  Either an erratum or an explicit correction in a future publication would satisfy me, though in the latter case I would ask, "What additional steps need to be completed before this future publication will be available, and how long do you anticipate that may take?"

If the future publication is still quite far away (by the standards of your field), then I would recommend an erratum in the meantime, which should do no harm.  I would not consider a long period of time since publication a very strong argument against providing an erratum.  Here is one famous paper in my field that received an erratum after 3.5 years.

A promise that no mistakes will happen in the future would strike me as naive and unrealistic.