*2.2. Direct and Indirect Income*

Prior research [21] identified four types of indicators of direct faculty income before and after job mobility: annual salary from one's HEI; other income from one's HEI; income from other academic institutions; and income from other employers. In addition, there are three indicators of indirect income [22]: research funds (which can be divided into vertical research and lateral research, with the former mainly from government agencies and the latter from industry); housing (because job negotiations often include this item); and spouse's income (because academic mobility is, to a great extent, not a personal but a family decision, or it is at least greatly affected by family).

### *2.3. Correlations Between Faculty Mobility and Faculty Prestige and Performance*

Scholars are keen to assess the impact of institutional prestige and academic performance on faculty mobility. Although there are certainly differences in the conclusions found in the literature, the mainstream view asserts that institutional prestige is more influential for position access and mobility than academic performance. For example, Caplow's [23] study of the mobility of liberal arts faculty found that during the mobility process, institutional prestige was more important than one's previous academic performance. Similarly, in the research of "Global inequality in the academic system", Gerhards [24] concluded that universities' symbolic capital seems to be more important than the quality of a department.
