SINGAPORE - A woman may be doing the same job as her male colleague, in the same industry, at the same age and education level, but for lower pay.

This adjusted gender pay gap was 6 per cent in 2018, according to a new study by the Ministry of Manpower (MOM) and National University of Singapore economist Jessica Pan, which was released on Thursday (Jan 9).

The gap has narrowed from 8.8 per cent in 2002, and is lower than the latest available figures from countries like the United States (8 per cent), Canada (7.7 per cent to 8.3 per cent) and China (18.3 per cent), said the ministry.

Overall, the median monthly salary of a woman in full-time work was 16.3 per cent less than a man in full-time work, a slight rise from 16 per cent in 2002.

The study is based on data for Singaporeans and permanent residents aged 25 to 54 taken from the Comprehensive Labour Force Survey of about 33,000 households.

The researchers used a statistical model to calculate the share of the gap that is due to various factors, namely human capital factors like age and education, and labour market factors like occupation, industry and working hours. Removing the effect of these factors results in the adjusted pay gap.

The effects of labour market factors on the median gender pay gap increased over the years.

"This suggests that despite women upgrading their occupations and improving their labour market attachment, gender differences in occupational wages had become larger due to occupation income growth favouring men," the researchers said in the report.

They found that occupation played the biggest role, accounting for 43 per cent of the pay gap in 2018. Its impact also increased over the years, as it only accounted for 16 per cent of the gap in 2002.

A possible reason for this could be that there is more occupational segregation today than in 2002, with men becoming increasingly over-represented in higher-paying occupations while women are taking up a larger share of roles in lower-paying occupations, the report said.

Alternatively, the degree of occupational segregation could be similar, but people in higher-paying occupations could have seen greater pay increases than people in lower-paying occupations.