University differences in the graduation minorities in STEM fields: evidence from California

We examine differences in minority science graduation rates among University of California campuses when racial preferences were in place. Less-prepared minorities at higher-ranked campuses had lower persistence rates in science and took longer to graduate. We estimate a model of students' college major choice where net returns of a science major differ across campuses and student preparation. We find less-prepared minority students at top- ranked campuses would have higher science graduation rates had they attended lower-ranked campuses. Better matching of science students to universities by preparation and providing information about students' prospects in different major-university combinations could increase minority science graduation

Identification and inference on regressions with missing covariate data

This paper examines the problem of identification and inference on a conditional moment condition model with missing data, with special focus on the case when the conditioning covariates are missing. We impose no assumption on the distribution of the missing data and we confront the missing data problem by using a worst case scenario approach. We characterize the sharp identified set and argue that this set is usually too complex to compute or to use for inference. Given this difficulty, we consider the construction of outer identified sets (i.e. supersets of the identified set) that are easier to compute and can still characterize the parameter of interest. Two different outer identification strategies are proposed. Both of these strategies are shown to have non-trivial identifying power and are relatively easy to use and combine for inferential purposes

Where versus What: College Value-Added and Returns to Field of Study in Further Education

We use administrative records on educational and labor market trajectories to estimate the value-added of English further education colleges in terms of educational and labor market outcomes and earnings returns to different fields of study taught at these colleges. We find that dispersion in college value-added in terms of labor market outcomes is moderate compared to differences in earnings returns across fields of study. We further show that value-added in labor market outcomes is correlated with value-added in academic outcomes. We conclude that in English further education, what one studies tends to matter more than where one does so

Assessing the effect of school days and absences on test score performance

Abstract While instructional time is viewed as crucial to learning, little is known about the effectiveness of reducing absences relative to increasing the number of school days. Using administrative data from North Carolina public schools, this paper jointly estimates the effect of absences and length of the school calendar on test score performance. We exploit a state policy that provides variation in the number of school days prior to standardized testing and find substantial differences between these two effects. Extending the school calendar by ten days increases math and reading test scores by only 1.7 and 0.8 of a standard deviation, respectively. A similar reduction in absences would lead to gains of 5.5 in math and 2.9 in reading. We perform a number of robustness checks including utilizing flu data to instrument for absences, family-year fixed effects, distinguishing between excused and unexcused absences, and controlling for a contemporaneous measure of student disengagement. Our results are robust to these alternative specifications. In addition, our findings indicate considerable heterogeneity across student ability, suggesting that targeting absenteeism among low performing students could aid in narrowing current gaps in performance

Does Affirmative Action Lead to Mismatch? A New Test and Evidence

We argue that once we take into account the students' rational enrollment decisions, mismatch in the sense that the intended beneficiary of affirmative action admission policies are made worse off could occur only if selective universities possess private information about students' post-enrollment treatment effects. This necessary condition for mismatch provides the basis for a new test. We propose an empirical methodology to test for private information in such a setting. The test is implemented using data from Campus Life and Learning Project (CLL) at Duke. Evidence shows that Duke does possess private information that is a statistically significant predictor of the students' post-enrollment academic performance. We also propose strategies to evaluate more conclusively whether the evidence of Duke private information has generated mismatch.

Teacher effectiveness and classroom composition

This paper studies how the effectiveness of teachers varies by classroom composition. We combine random assignment of teachers to classrooms with rich measures of teacher effectiveness based on a popular observational protocol, Framework for Teaching, to overcome key endogeneity concerns related to measurement and matching. We find that complementarities between classroom composition and teaching practice play a significant role in student achievement. We identify two main mechanisms that are driving this result: 1) negative interactions between challenging and/or student-centered practices and heterogeneity in classroom prior achievement, and 2) positive interactions between classroom management skills and average classroom prior achievement. Our findings illustrate the multidimensional nature of teacher effectiveness and have important implications for prescribing teaching practice and evaluating teachers. Simulations show that teacher rankings change substantially simply from within-school classroom reallocations, suggesting the need for caution when using popular teaching evaluation rubrics in high-stakes settings

Monitoring of chicken meat freshness by means of a colorimetric sensor array

A new optoelectronic nose to monitor chicken meat ageing has been developed. It is based on 16 pigments prepared by the incorporation of different dyes (pH indicators, Lewis acids, hydrogenbonding derivatives, selective probes and natural dyes) into inorganic materials (UVM-7, silica and alumina). The colour changes of the sensor array were characteristic of chicken ageing in a modi¿ed packaging atmosphere (30% CO2¿70% N2). The chromogenic array data were processed with qualitative (PCA) and quantitative (PLS) tools. The PCA statistical analysis showed a high degree of dispersion, with nine dimensions required to explain 95% of variance. Despite this high dimensionality, a tridimensional representation of the three principal components was able to differentiate ageing with 2-day intervals. Moreover, the PLS statistical analysis allows the creation of a model to correlate the chromogenic data with chicken meat ageing. The model offers a PLS prediction model for ageing with values of 0.9937, 0.0389 and 0.994 for the slope, the intercept and the regression coef¿cient, respectively, and is in agreement with the perfect ¿t between the predicted and measured values observed. The results suggest the feasibility of this system to help develop optoelectronic noses that monitor food freshness.Salinas Soler, Y.; Ros-Lis, JV.; Vivancos, J.; Martínez Mañez, R.; Marcos Martínez, MD.; Aucejo Romero, S.; Herranz, N.... (2012). Monitoring of chicken meat freshness by means of a colorimetric sensor array. Analyst. 137(16):3635-3643. doi:10.1039/C2AN35211GS3635364313716Anang, D. M., Rusul, G., Ling, F. H., & Bhat, R. (2010). Inhibitory effects of lactic acid and lauricidin on spoilage organisms of chicken breast during storage at chilled temperature. International Journal of Food Microbiology, 144(1), 152-159. doi:10.1016/j.ijfoodmicro.2010.09.014HINTON, A., & INGRAM, K. D. (2005). Microbicidal Activity of Tripotassium Phosphate and Fatty Acids toward Spoilage and Pathogenic Bacteria Associated with Poultry. Journal of Food Protection, 68(7), 1462-1466. doi:10.4315/0362-028x-68.7.1462Jeremiah, L. . (2001). Packaging alternatives to deliver fresh meats using short- or long-term distribution. Food Research International, 34(9), 749-772. doi:10.1016/s0963-9969(01)00096-5Ellis, D. I., & Goodacre, R. (2001). Rapid and quantitative detection of the microbial spoilage of muscle foods: current status and future trends. Trends in Food Science & Technology, 12(11), 414-424. doi:10.1016/s0924-2244(02)00019-5Vinci, G., & Antonelli, M. . (2002). Biogenic amines: quality index of freshness in red and white meat. Food Control, 13(8), 519-524. doi:10.1016/s0956-7135(02)00031-2Lovestead, T. M., & Bruno, T. J. (2010). Detection of poultry spoilage markers from headspace analysis with cryoadsorption on a short alumina PLOT column. Food Chemistry, 121(4), 1274-1282. doi:10.1016/j.foodchem.2010.01.044Bota, G. M., & Harrington, P. B. (2006). Direct detection of trimethylamine in meat food products using ion mobility spectrometry. Talanta, 68(3), 629-635. doi:10.1016/j.talanta.2005.05.001Grau, R., Sánchez, A. J., Girón, J., Iborra, E., Fuentes, A., & Barat, J. M. (2011). Nondestructive assessment of freshness in packaged sliced chicken breasts using SW-NIR spectroscopy. Food Research International, 44(1), 331-337. doi:10.1016/j.foodres.2010.10.011Sahar, A., Boubellouta, T., & Dufour, É. (2011). Synchronous front-face fluorescence spectroscopy as a promising tool for the rapid determination of spoilage bacteria on chicken breast fillet. Food Research International, 44(1), 471-480. doi:10.1016/j.foodres.2010.09.006Lin, M., Al-Holy, M., Mousavi-Hesary, M., Al-Qadiri, H., Cavinato, A. G., & Rasco, B. A. (2004). Rapid and quantitative detection of the microbial spoilage in chicken meat by diffuse reflectance spectroscopy (600-1100 nm). Letters in Applied Microbiology, 39(2), 148-155. doi:10.1111/j.1472-765x.2004.01546.xMartínez-Máñez, R., & Sancenón, F. (2003). Fluorogenic and Chromogenic Chemosensors and Reagents for Anions. Chemical Reviews, 103(11), 4419-4476. doi:10.1021/cr010421eAmendola, V., Fabbrizzi, L., & Mosca, L. (2010). Anion recognition by hydrogen bonding: urea-based receptors. Chemical Society Reviews, 39(10), 3889. doi:10.1039/b822552bQuang, D. T., & Kim, J. S. (2010). Fluoro- and Chromogenic Chemodosimeters for Heavy Metal Ion Detection in Solution and Biospecimens. Chemical Reviews, 110(10), 6280-6301. doi:10.1021/cr100154pAmendola, V., Bonizzoni, M., Esteban-Gómez, D., Fabbrizzi, L., Licchelli, M., Sancenón, F., & Taglietti, A. (2006). Some guidelines for the design of anion receptors. Coordination Chemistry Reviews, 250(11-12), 1451-1470. doi:10.1016/j.ccr.2006.01.006Chen, X., Zhou, Y., Peng, X., & Yoon, J. (2010). Fluorescent and colorimetric probes for detection of thiols. Chemical Society Reviews, 39(6), 2120. doi:10.1039/b925092aMohr, G. J. (2006). New chromogenic and fluorogenic reagents and sensors for neutral and ionic analytes based on covalent bond formation–a review of recent developments. Analytical and Bioanalytical Chemistry, 386(5), 1201-1214. doi:10.1007/s00216-006-0647-3Kerry, J. P., O’Grady, M. N., & Hogan, S. A. (2006). Past, current and potential utilisation of active and intelligent packaging systems for meat and muscle-based products: A review. Meat Science, 74(1), 113-130. doi:10.1016/j.meatsci.2006.04.024Rakow, N. A., & Suslick, K. S. (2000). A colorimetric sensor array for odour visualization. Nature, 406(6797), 710-713. doi:10.1038/35021028Lim, S. H., Kemling, J. W., Feng, L., & Suslick, K. S. (2009). A colorimetric sensor array of porous pigments. The Analyst, 134(12), 2453. doi:10.1039/b916571aPalacios, M. A., Nishiyabu, R., Marquez, M., & Anzenbacher, P. (2007). Supramolecular Chemistry Approach to the Design of a High-Resolution Sensor Array for Multianion Detection in Water. Journal of the American Chemical Society, 129(24), 7538-7544. doi:10.1021/ja0704784Wu, Y., Na, N., Zhang, S., Wang, X., Liu, D., & Zhang, X. (2009). Discrimination and Identification of Flavors with Catalytic Nanomaterial-Based Optical Chemosensor Array. Analytical Chemistry, 81(3), 961-966. doi:10.1021/ac801733kJanzen, M. C., Ponder, J. B., Bailey, D. P., Ingison, C. K., & Suslick, K. S. (2006). Colorimetric Sensor Arrays for Volatile Organic Compounds. Analytical Chemistry, 78(11), 3591-3600. doi:10.1021/ac052111sSuslick, B. A., Feng, L., & Suslick, K. S. (2010). Discrimination of Complex Mixtures by a Colorimetric Sensor Array: Coffee Aromas. Analytical Chemistry, 82(5), 2067-2073. doi:10.1021/ac902823wHuang, X., Xin, J., & Zhao, J. (2011). A novel technique for rapid evaluation of fish freshness using colorimetric sensor array. Journal of Food Engineering, 105(4), 632-637. doi:10.1016/j.jfoodeng.2011.03.034Anzenbacher, Jr., P., Lubal, P., Buček, P., Palacios, M. A., & Kozelkova, M. E. (2010). A practical approach to optical cross-reactive sensor arrays. Chemical Society Reviews, 39(10), 3954. doi:10.1039/b926220mRos-Lis, J. V., García, B., Jiménez, D., Martínez-Máñez, R., Sancenón, F., Soto, J., … Valldecabres, M. C. (2004). Squaraines as Fluoro−Chromogenic Probes for Thiol-Containing Compounds and Their Application to the Detection of Biorelevant Thiols. Journal of the American Chemical Society, 126(13), 4064-4065. doi:10.1021/ja031987iRos-Lis, J. V., Martínez-Máñez, R., Rurack, K., Sancenón, F., Soto, J., & Spieles, M. (2004). Highly Selective Chromogenic Signaling of Hg2+in Aqueous Media at Nanomolar Levels Employing a Squaraine-Based Reporter. Inorganic Chemistry, 43(17), 5183-5185. doi:10.1021/ic049422qRos-Lis, J. V., Marcos, M. D., Mártinez-Máñez, R., Rurack, K., & Soto, J. (2005). A Regenerative Chemodosimeter Based on Metal-Induced Dye Formation for the Highly Selective and Sensitive Optical Determination of Hg2+ Ions. Angewandte Chemie International Edition, 44(28), 4405-4407. doi:10.1002/anie.200500583Ros-Lis, J. V., Martínez-Máñez, R., & Soto, J. (2005). Colorimetric Signaling of Large Aromatic Hydrocarbons via the Enhancement of Aggregation Processes. Organic Letters, 7(12), 2337-2339. doi:10.1021/ol050564dCliment, E., Marcos, M. D., Martínez-Máñez, R., Sancenón, F., Soto, J., Rurack, K., & Amorós, P. (2009). The Determination of Methylmercury in Real Samples Using Organically Capped Mesoporous Inorganic Materials Capable of Signal Amplification. Angewandte Chemie International Edition, 48(45), 8519-8522. doi:10.1002/anie.200904243Ábalos, T., Jiménez, D., Martínez-Máñez, R., Ros-Lis, J. V., Royo, S., Sancenón, F., … Parra, M. (2009). Hg2+ and Cu2+ selective detection using a dual channel receptor based on thiopyrylium scaffoldings. Tetrahedron Letters, 50(27), 3885-3888. doi:10.1016/j.tetlet.2009.04.060Climent, E., Giménez, C., Marcos, M. D., Martínez-Máñez, R., Sancenón, F., & Soto, J. (2011). Selective and sensitive chromo-fluorogenic sensing of anionic surfactants in water using functionalised silica nanoparticles. Chemical Communications, 47(24), 6873. doi:10.1039/c1cc11393cRoyo, S., Costero, A. M., Parra, M., Gil, S., Martínez-Máñez, R., & Sancenón, F. (2011). Chromogenic, Specific Detection of the Nerve-Agent Mimic DCNP (a Tabun Mimic). Chemistry - A European Journal, 17(25), 6931-6934. doi:10.1002/chem.201100602García-Acosta, B., Comes, M., Bricks, J. L., Kudinova, M. A., Kurdyukov, V. V., Tolmachev, A. I., … Amorós, P. (2006). Sensory hybrid host materials for the selective chromo-fluorogenic detection of biogenic amines. Chem. Commun., (21), 2239-2241. doi:10.1039/b602497aSancenón, F., Descalzo, A. B., Martínez-Máñez, R., Miranda, M. A., & Soto, J. (2001). A Colorimetric ATP Sensor Based on 1,3,5-Triarylpent-2-en-1,5-diones. Angewandte Chemie International Edition, 40(14), 2640-2643. doi:10.1002/1521-3773(20010716)40:143.0.co;2-aEsteban, J., Ros-Lis, J. V., Martínez-Máñez, R., Marcos, M. D., Moragues, M., Soto, J., & Sancenón, F. (2010). Sensitive and Selective Chromogenic Sensing of Carbon Monoxide by Using Binuclear Rhodium Complexes. Angewandte Chemie International Edition, 49(29), 4934-4937. doi:10.1002/anie.201001344Moragues, M. E., Esteban, J., Ros-Lis, J. V., Martínez-Máñez, R., Marcos, M. D., Martínez, M., … Sancenón, F. (2011). Sensitive and Selective Chromogenic Sensing of Carbon Monoxide via Reversible Axial CO Coordination in Binuclear Rhodium Complexes. Journal of the American Chemical Society, 133(39), 15762-15772. doi:10.1021/ja206251rRos-Lis, J. V., Martínez-Máñez, R., Sancenón, F., Soto, J., Rurack, K., & Weißhoff, H. (2007). Signalling Mechanisms in Anion-Responsive Push-Pull Chromophores: The Hydrogen-Bonding, Deprotonation and Anion-Exchange Chemistry of Functionalized Azo Dyes. European Journal of Organic Chemistry, 2007(15), 2449-2458. doi:10.1002/ejoc.200601111El Haskouri, J., Zárate, D. O. de, Guillem, C., Latorre, J., Caldés, M., Beltrán, A., … Amorós, P. (2002). Silica-based powders and monoliths with bimodal pore systemsElectronic supplementary information (ESI) available: UV–Vis spectrum of sample 3. See http://www.rsc.org/suppdata/cc/b1/b110883b/. Chemical Communications, (4), 330-331. doi:10.1039/b110883bDe Jong, S. (1993). SIMPLS: An alternative approach to partial least squares regression. 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Mesoporous silica materials with covalently anchored phenoxazinone dyes as fluorescent hybrid materials for vapour sensing. Journal of Materials Chemistry, 17(44), 4716. doi:10.1039/b707473eDescalzo, A. B., Rurack, K., Weisshoff, H., Martínez-Máñez, R., Marcos, M. D., Amorós, P., … Soto, J. (2005). Rational Design of a Chromo- and Fluorogenic Hybrid Chemosensor Material for the Detection of Long-Chain Carboxylates. Journal of the American Chemical Society, 127(1), 184-200. doi:10.1021/ja045683nComes, M., Aznar, E., Moragues, M., Marcos, M. D., Martínez-Máñez, R., Sancenón, F., … Amorós, P. (2009). Mesoporous Hybrid Materials Containing Nanoscopic «Binding Pockets» for Colorimetric Anion Signaling in Water by using Displacement Assays. Chemistry - A European Journal, 15(36), 9024-9033. doi:10.1002/chem.200900890Nychas, G.-J. E., & Tassou, C. C. (1997). Spoilage Processes and Proteolysis in Chicken as Detected by HPLC. 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Racial segregation patterns in selective universities

This paper examines sorting into interracial friendships at selective universities. We show significant friendship segregation, particularly for blacks. Indeed, black friendships are no more diverse in college than in high school despite the colleges blacks attend having substantially smaller black populations. We show that part of the reason for the segregation patterns is large differences in academic background coupled with students being more likely to form friendships with those of similar academic backgrounds. Within a school, stronger academic backgrounds make interracial friendships with blacks less likely and friendships with Asians more likely. These results suggest that affirmative action admission policies at selective universities which drive a wedge between the academic characteristics of different racial groups may result in increased within school segregation

Catching up to girls: understanding the gender imbalance in educational attainment within race

We estimate a sequential model of schooling to assess the major contributing factors to the large gender imbalance in educational attainment within racial groups. First, we find that differences between males and females in measures of early behavior account for the majority of the gender gap for each racial group. Second, we show that black males have the largest response to improvements in family background characteristics, such that equalizing the distribution of family background characteristics for black and white youths reduces the gender gap in college enrollment among black youth by 50%