These estimates conflate the short- and medium-term effects of mobility, however. Although it could be that all effects of mobility are due to the disruption in the year of the move itself, it is also possible that effects of mobility due to changes in curriculum or peers take longer to materialize and are therefore only observed in the medium term, or it could be that mobility had both short-term and medium-term effects. To gain a further understanding of when mobility matters relative to the year of the move itself, we parse the short-term and medium-term effects of mobility. As shown in table 5, we see that structural moves have significant negative impacts on student performance for both ELA and math in the medium term, and an additional negative impact on short-term ELA performance.23 In ELA, students perform an additional 0.052–0.059 worse in the year of the move itself with small negative effects in the years following the move. In math, there is no differential impact in the year of the move itself but students perform significantly worse in all years following a structural move (0.176–0.186). By contrast, nonstructural moves appear to have lasting positive effects in ELA (0.156–0.275) with no additional impact experienced in the year of the move itself. Nonstructural moves have no significant impact on math performance, however. Thus, these estimates provide consistent evidence that structural moves harm student math and ELA performance in the medium-term, and nonstructural moves appear to have a positive effect in ELA in the medium-term. Furthermore, these results highlight the importance of separating the short-term versus medium-term impacts of mobility, as table 4 masks the result that the impacts of nonstructural mobility may take longer to appear.

Table 5.
Instrumental Variable Results, Short-Term and Medium-Term Effects of Structural and Nonstructural Moves, ELA and Math Exams
ELAMath
(1)(2)(3)(4)
Post-summer move
Structural −0.033 −0.047*** −0.186*** −0.176***
(0.024) (0.018) (0.034) (0.024)
Nonstructural 0.275** 0.156* 0.115 −0.040
(0.109) (0.083) (0.149) (0.107)
Move in year t
Structural −0.059*** −0.052*** 0.022 −0.001
(0.019) (0.015) (0.022) (0.015)
Nonstructural −0.005 −0.024 0.242* 0.074
(0.113) (0.067) (0.127) (0.071)
Instruments
Building sale
Nonparametric
Observations 342,685 342,685 343,832 343,832
Unique students 88,241 88,241 88,254 88,254
ELAMath
(1)(2)(3)(4)
Post-summer move
Structural −0.033 −0.047*** −0.186*** −0.176***
(0.024) (0.018) (0.034) (0.024)
Nonstructural 0.275** 0.156* 0.115 −0.040
(0.109) (0.083) (0.149) (0.107)
Move in year t
Structural −0.059*** −0.052*** 0.022 −0.001
(0.019) (0.015) (0.022) (0.015)
Nonstructural −0.005 −0.024 0.242* 0.074
(0.113) (0.067) (0.127) (0.071)
Instruments
Building sale