The labour ministry also said its sample size for wage data for October last year was smaller than it should have been due to polling errors, according to a statement.
The ministry on Friday revised regular wage data from January 2012 to October 2018 to partially rectify the polling errors.
Labour Minister Takumi Nemoto told reporters he is still investigating the motives behind the polling errors.
Labour ministry officials admitted on Wednesday that they have issued monthly wage data without meeting sampling standards for years, hurting the credibility of a key gauge of the success of Prime Minister Shinzo Abe's economic policies.
(Reporting by Stanley White; Editing by Shri Navaratnam)
