Table 2.

The Relationship between Methodological Choices and the Estimated Diversionary Effects of Community College Entrance: Results from Studies That Restrict Treatment to Transfer Students.

	Meta-regression models
	Model 1			Model 2			Model 3			Model 4			Model 5a
Variable	$\beta \left(SE\right)$	$df$	$p$	$\beta \left(SE\right)$	$df$	$p$	$\beta \left(SE\right)$	$df$	$p$	$\beta \left(SE\right)$	$df$	$p$	$\beta \left(SE\right)$	$df$	$p$
Intercept Sample restrictions	−.04 (.02)	46.7	.075	−.06 (.02)	41.8	.008	−.05 (.02)	41.6	.032	−.06 (.02)	42.6	.01 1	−.06 (.02)	22.7	.008
Different cohort defmition				. 15 (.06)	2.0	.128	. 16 (.06)	2.0	.124	. 15 (.06)	2.2	.1 17	. 15 (.06)	2.5	.095
Baccalaureate aspirations Identification strategyb				.02 (.07)	1.0	.840	−.06 (.04)	l.l	.346	−.08 (.05)	l.l	.292	−.14 (.12)	1.2	.451
Regression							.04 (.05)	2.1	.523	.02 (.05)	l.l	.707	.02 (.05)	1.2	.695
PSM							. 17 (.06)	1.7	.131	.14 (.07)	1.2	.261	.14 (.07)	1.2	.259
Exogenous variation Statistical controls							.12 (.03)	2.2	.053	.08 (.03)	1.3	.146	.08 (.02)	1.3	.137
Background										.05 (.00)	1.4	.000	.05 (.00)	2.6	.000
Aspirations										−.04 (.05)	1.2	.526	−.06 (.05)	1.2	.420
Enrollment pattern Data characteristics										−. 17 (.05)	1.5	.1 14	−. 17 (.06)	1.5	.127
Year began collegec													.00 (.00)	14.5	.096
Years follow-upc													.03 (.02)	7.3	.238
Control group graduationc Variance components													−.46 (. 13)	16.0	.003
Study level	.00 (.01)			.01 (.01)			.01 (.01)			.01 (.01)			.01 (.01)
Data level	.02 (.01)			.01 (.01)			.01 (.01)			.01 (.01)			.01 (.00)

Note: The analytic sample includes 31 studies with 48 data sources and 72 effect sizes. The table presents unstandardized coefficients ($\mathrm{\beta }$), Standard errors $\left(SE\right)$, degrees of freedom ($df$), and $p$ values ($p$) obtained from mixed-effects meta-regression models using robust standard errors and an estimated intercorrelation within author/data-source clusters of 0.80. $\mathrm{\beta }$ represents the change in the risk difference for every one-unit change in the predictor. Intercept $\mathrm{\beta }$ represents the estimated risk difference for entering a community college while holding other measures in the model at their means (all variables are grand-mean centered). Coefficients in bold are statistically significant ($p<.05$ when $df>4.0$; $p<.01$ when $df<4.0$). PSM = propensity score matching.

^aIn Model 5, we drop one study, Gonzales (1999), that does not provide information about the length of follow-up. We ran additional analyses including Gonzales (1999) and dropping the years follow-up measure; this did not alter the patterns of effects.

^bReference category is mean comparison.

^cContinuous variable.