Fig. 3From: Union membership and the wage gap between the public and private sectors: evidence from ChinaSource: Calculated using data from the CFPS of 2010, 2012, 2014, 2016 and 2018. The results of province-level regional dummy variables were not presented in Fig. 3. These results are available upon requestStandardized bias across control variables among unmatched and matched group (total samples). Back to article page