Demographic characteristics and scores of Chinese migrants among different SMEs (<i>n</i> = 856).

P≤0.05, **P≤0.01, ***P≤0.001, △P≤0.05 (compared with the first option),▽P≤0.05 (compared with the second option), □P≤0.01 (compared with the second and third option). : the statistics for chi-squared test; t: the statistics for t-test; F: the statistics for Analysis of variance (ANOVA); PCS: physical component summary; MCS: mental component summary; h: hour; ¥: the currency symbol of RMB. Note: Most of the variables' categories follow the national migrants' survey [3]. the mean age of Chinese migrants were 27.9 in 2011,thus the age variable was divided into two categories (>27.9 and ≤27.9). The monthly income of migrants was divided into four group “<¥2000”, “<¥2500”, “<¥3000” and “¥3000+”. Our following results also suggested they were reasonable categorization with an equal sample in each group. Migrants often felt lonely and had less social support when they did not live with their family members. The term “family separation” could convey this meaning, but “divorced or widowed, married, and single” did not. The education was categorized by “primary school or less, junior middle school and high school or above.