Q: Can I change the data in my study after the paper has been published in a journal?
It is not clear why you would want to change data in a study that has already been published. Under normal circumstances, you would not be allowed to do that since the study has been evaluated by peer reviewers before being published.
However, if you have detected an error in your paper that the peer reviewers missed, and if that error is a serious one, it should be corrected. In that case, you should write to the journal mentioning the error, the correction, and how it can impact your paper. The journal will then either update the online version or add a note, comment, or erratum.
Related reading:
U can't change a data in already published paper. However, if the there is typographical error that compromise interpretation of your findings you can notify the editor of the journal for possible erratum or corrigendum. i
