Impact of Changes in Public Officials Recruitment Test Subjects on Public Service Motivation: A Difference-in-Differences (DID) Approach

In 2017, the subject ‘Constitution' was added to the Open Competitive Examination for Grade 5 public officials to strengthen the assessment of public service values among applicants. This study examines the impact of this new subject on Public Service Motivation (PSM) among newly recruited Grade 5 public officials. Survey data spanning from 2013 to 2023 from the Korea Institute of Public Administration was utilized to measure PSM. The study employed the Difference-in-Differences (DID) method, a quasi-experimental design technique, to enhance causal inference. The treatment group consisted of new Grade 5 public officials, while the control group comprised new Grade 7 public officials. Visual and statistical tests confirmed the parallel trend assumption. Despite a decade-long decline in PSM scores for both groups, the introduction of the 'Constitution' subject resulted in a 0.127-point increase in PSM scores among new Grade 5 public officials. This suggests that the changes in examination subjects effectively achieved their intended objective by selecting individuals with high public service motivation. Unlike other countries with intense competition for public official positions, Korea did not experience adverse selection issues, where individuals with low PSM were recruited.