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Comparing Like with Like: The Role of Student and School Characteristics in Value-Added Models. Kilchan Choi Kyo Yamashiro Michael Seltzer Joan Herman CRESST Conference 2004 University of California, Los Angeles. Value - Added Models (VAM). Concerned with residual gains/growth
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Comparing Like with Like: The Role of Student and School Characteristics in Value-Added Models Kilchan Choi Kyo Yamashiro Michael Seltzer Joan Herman CRESST Conference 2004University of California, Los Angeles
Value-Added Models (VAM) • Concerned with residual gains/growth • In general, residuals are sensitive to controls and adjustments • Results are highly dependent on extent to which model adjusts for background characteristics
Adjusting for Background Characteristics in VAM • School effectiveness literature still searching for appropriate ways to adjust for background characteristics • Type A: adjustment of student background (Sj), yet no adjustment of school-level contextual effects (Cj) and school policies and practices effects (Pj) • Type B: adjustment of student background (Sj) and contextual effects (Cj)
Type A Effects • Type A effect: Aj = [j0– (0 + sSj)] = 1Pj + 2Cj = Uj • Includes effects of Pj & Cj, and wider social influences • Even if Pj and Cj aren’t observed, Uj captures Type A effect • Performance levels adjusted only for student background characteristics • Students and parents are particularly interested in this effect(shows parents how their child would do in a given school)
Type B Effects • Type B effect: Bj=[j0 – (0+ sSj + 2Cj)] = 1Pj + Uj • Like Type A, adjusts for student background • Includes effects of Pj and excludes factors that lie outside their control (Cj) • Allows for comparison among schools which are similar in terms of their social class and wider social influences • Issue: If Pj and Cj are correlated, Type B effects are likely to be under- or over-estimated (Raudenbush, 2004) • Teachers and principals would be more interested in this effect(fairer comparison)
Data Structure • Diverse urban school district in Pacific NW • 2,524 Students across 72 Schools • Average # students/school: 35 • Average % qualifying for FRPL: 36.2% • Average % Minority (African American, Native American, or Latino): 68.6% • 2 time-point ITBS reading scores (Grade 3 in 2001 & Grade 5 in 2003) • Standard Errors of Measurement (SE) on ITBS reading scores (Bryk et al., 1998)
Latent Variable Hierarchical Gains Model (LVR-HM) • Level 1: Time Series within Student • Obtaining initial status and gain for each student i with standard errors • Level 2: Student Level • Gain for student i is modeled as function of his or her initial status (& SES) • Level 3: School Level • Gain for school j is modeled as function of school’s initial status (& SES)
Models Compared • Mod 1: 3-level Unconditional Gains (no adj.) • Mod 2: + Student IS (initial status) • Mod 3:+ Student SES • Mod 4: + Student IS + Student SES • Mod 5: + Student IS + Student SES + School Mean IS • Mod 6: + Student IS + Student SES + School Mean IS + School Mean SES
What adjustments make for a fair comparison? residual school
What adjustments make for a fair comparison of school effectiveness? • Lev 2: Student SES adds very little once you control for Student IS • Lev 3: Adding in School SES may be over-adjusting for contextual effects and may be taking out some of the school effects we are looking for (Raudenbush, 2004 in JEBS) • After adjusting for Student IS & SES, contextual effect of mean IS turns out to be insignificant, while contextual effect of mean SES is significant
Philosophical Challenge • Should determinations of school effectiveness be based on absolute performance (AYP model) OR performance conditioned on things outside the school’s control (VAM, e.g., schoolwide background characteristics) and starting points? • Probably both, but need to be aware of potential over-adjustment
School B: Highest Gain School C: Low IS, High Gain School A: Highest IS School D: Low IS, Better than exp gain School E: Med IS, Lower than exp gain School Initial Status vs. Gain
Methodological/Measurement Challenge If Policy/Practice (P) and Contextual (C) effects are correlated, will part of the true school effect be removed when controlling for C? Need empirical information on: • Adequate measures of Policy & Practice • The degree to which these aspects (P&C) are correlated