Abstract
This study introduces a co-twin control method commonly used in the medical literature but not often within educational research. This method allows for a comparison of twins discordant for an “exposure,” approximating alternative outcomes in the counterfactual model. Example analyses use data drawn from the Florida Twin Project on Reading to determine whether exposure to “teacher quality,” measured by growth in oral reading fluency (ORF) scores of classmates, causally affects ORF performance of twins in the subsequent years. The analysis highlights PROC MIXED in SAS, including a novel expansion to allow for the nested data. Results from 2,788 twins suggested that being in classrooms with lower teacher quality in first grade leads to lower ORF scores in second and third grade with little indication of possible genetic or environmental confounding.
|
Bergen, S. E., Gardner, C. O., Aggen, S. H., Kendler, K. S. (2008). Socioeconomic status and social support following illicit drug use: Causal pathways or common liability? Twin Research and Human Genetics, 11, 266–274. Google Scholar | Crossref | Medline | ISI | |
|
Burt, S. A., Donnellan, M. B., Humbad, M. N., Hicks, B. M., McGue, M., Iacono, W. G. (2010). Does marriage inhibit antisocial behavior? An examination of selection vs causation via a longitudinal twin design. Archives of General Psychiatry, 67, 1309–1315. Google Scholar | Crossref | Medline | |
|
Byrne, B., Coventry, W. L., Olson, R. K., Samuelsson, S., Corley, R., Willcutt, E. G., . . . Defries, J. C. (2009). Genetic and environmental influences on aspects of literacy and language in early childhood: Continuity and change from preschool to Grade 2. Journal of Neurolinguistics, 22, 219–236. Google Scholar | Crossref | Medline | ISI | |
|
Byrne, B., Coventry, W. L., Olson, R. K., Wadsworth, S. J., Samuelsson, S., Petrill, S. A., . . . Corley, R. (2010). “Teacher effects” on early literacy development: Evidence from a study of twins. Journal of Educational Psychology, 102, 32–42. Google Scholar | Crossref | Medline | ISI | |
|
Carr, A. B., Martin, N. G., Whitfield, J. B. (1981). Usefulness of the co-twin control design in investigations as exemplified in a study of effects of ascorbic acid on laboratory test results. Clinical Chemistry, 27, 1469–1470. Google Scholar | Medline | ISI | |
|
Chall, J. S., Jacobs, V. A., Baldwin, L. E. (1990). The reading crisis: Why poor children fall behind. Boston, MA: Harvard University Press. Google Scholar | |
|
Connor, C. M., Morrison, F. J., Fishman, B. J., Schatschneider, C., Underwood, P. (2007). Algorithm-guided individualized reading instruction. Science, 315, 464–465. Google Scholar | Crossref | Medline | ISI | |
|
Connor, C. M., Son, S. H., Hindman, A. H., Morrison, F. J. (2005). Teacher qualifications, classroom practices, family characteristics, and preschool experience: Complex effects on first graders’ vocabulary and early reading outcomes. Journal of School Psychology, 43, 343–375. Google Scholar | Crossref | ISI | |
|
DeThorne, L. S., Hart, S. A. (2009). Use of the twin design to examine evocative gene-environment effects within a conversational context. European Journal of Developmental Science, 3, 175–194. Google Scholar | Medline | |
|
DeThorne, L. S., Petrill, S. A., Hart, S. A., Channell, R. W., Campbell, R. J., Deater-Deckard, K., . . . Vandenbergh, D. J. (2008). Genetic effects on children’s conversational language use. Journal of Speech, Language, and Hearing Research, 51, 423–435. Google Scholar | Crossref | Medline | ISI | |
|
Francis, D. J., Santi, K. L., Barr, C., Fletcher, J. M., Varisco, A., Foorman, B. R. (2008). Form effects on the estimation of students’ oral reading fluency using DIBELS. Journal of School Psychology, 46, 315–342. Google Scholar | Crossref | Medline | ISI | |
|
Fuchs, L. S., Fuchs, D., Hosp, M. K., Jenkins, J. R. (2001). Oral reading fluency as an indicator of reading competence: A theoretical, empirical, and historical analysis. Scientific Studies of Reading, 5, 239–256. Google Scholar | Crossref | |
|
Greenwald, R., Hedges, L. V., Laine, R. D. (1996). The effect of school resources on student achievement. Review of Educational Research, 66, 361–396. Google Scholar | SAGE Journals | ISI | |
|
Kaminski, R. A., Good, R. H. (2003). DIBELS: Dynamic Indicators of Basic Early Literacy Skills. Frederick, CO: Sopris West. Google Scholar | |
|
Levitt, S. D., List, J. A. (2007). What do laboratory experiments measuring social preferences reveal about the real world? Journal of Economic Perspectives, 21, 153–174. Google Scholar | Crossref | ISI | |
|
McGue, M., Osler, M., Christensen, K. (2010). Causal inference and observational research. Perspectives on Psychological Science, 5, 546–556. Google Scholar | SAGE Journals | ISI | |
|
McLoyd, V. C. (1998). Socioeconomic disadvantage and child development. American Psychologist, 53, 185–204. Google Scholar | Crossref | Medline | ISI | |
|
Morgan, S. L., Winship, C. (2007). Counterfactuals and Causal Inference. New York, NY: Cambridge University Press. Google Scholar | Crossref | |
|
Najarian, M., Snow, K., Lennon, J., Kinsey, S. (2010). Early Childhood Longitudinal Study, Birth Cohort (ECLS-B), Preschool–Kindergarten 2007 Psychometric Report (Report No. NCES 2010-009). Washington, DC: National Center for Education Statistics, Institute of Education Sciences, U.S. Department of Education. Google Scholar | |
|
National Early Literacy Panel . (2008). Developing early literacy: A scientific synthesis of early literacy development and implicatons for intervention. Washington, DC: National Institute for Literacy. Google Scholar | |
|
Nye, B., Konstantopoulos, S., Hedges, L. V. (2004). How large are teacher effects? Educational Evaluation and Policy Analysis, 26, 237–257. Google Scholar | SAGE Journals | ISI | |
|
Petrill, S. A., Hart, S. A., Harlaar, N., Logan, J., Justice, L. M., Schatschneider, C., . . . Cutting, L. (2010). Genetic and environmental influences on the growth of early reading skills. Journal of Child Psychology and Psychiatry, 51, 660–667. Google Scholar | Crossref | Medline | ISI | |
|
Petscher, Y., Kim, Y. S. (2011). The utility and accuracy of oral reading fluency score types in predicting reading comprehension. Journal of School Psychology, 49, 107–129. Google Scholar | Crossref | Medline | ISI | |
|
Plomin, R., DeFries, J. C., McClearn, G. E., McGuffin, P. (2008). Behavioral Genetics (5th ed.). New York, NY: Worth Publishers. Google Scholar | |
|
Plomin, R., Haworth, C. (2010). Genetics and intervention research. Perspectives on Psychological Science, 5, 557–563. Google Scholar | SAGE Journals | ISI | |
|
Plomin, R., Kovas, Y. (2005). Generalist genes and learning disabilities. Psychological Bulletin, 131, 592–617. Google Scholar | Crossref | Medline | ISI | |
|
Roberts, G., Good, R., Corcoran, S. (2005). Story retell: A fluency-based indicator of reading comprehension. School Psychology Quarterly, 20, 304–317. Google Scholar | Crossref | ISI | |
|
Rodgers, J. L., Johnson, A. B., Bard, D. E. (2005). NLSY-children/young adult (1986-2000) kinship linking algorithm. Unpublished manuscript, University of Oklahoma, Norman. Google Scholar | |
|
Roehrig, A. D., Petscher, Y., Nettles, S. M., Hudson, R. F., Torgesen, J. K. (2008). Accuracy of the DIBELS oral reading fluency measure for predicting third grade reading comprehension outcomes. Journal of School Psychology, 46, 343–366. Google Scholar | Crossref | Medline | ISI | |
|
Rutter, M. (2007). Proceeding from observed correlation to causal inference: The use of natural experiments. Perspectives on Psychological Science, 2, 377–395. Google Scholar | SAGE Journals | ISI | |
|
Scarborough, H. S., Dobrich, W., Hager, M. (1991). Preschool literacy experience and later reading achievement. Journal of Learning Disabilities, 24, 508–511. Google Scholar | SAGE Journals | ISI | |
|
Shadish, W. R., Cook, T. D., Campbell, D. T. (2002). Experimental and Quasi-Experimental Designs for Generalized Causal Influence. Boston, MA: Houghton Mifflin. Google Scholar | |
|
Shavelson, R. J., Towne, L. (2002). Scientific Research in Education. Washington, DC: National Academies Press. Google Scholar | |
|
Singer, J. D. (1998). Using SAS PROC MIXED to fit multilevel models, hierarchical models, and individual growth models. Journal of Educational and Behavioral Statistics, 24, 323–355. Google Scholar | SAGE Journals | |
|
Speece, D. L., Case, L. P. (2001). Classification in context: An alternative approach to identifying early reading disability. Journal of Educational Psychology, 93, 735–749. Google Scholar | Crossref | ISI | |
|
Strayer, L. C. (1930). Language and growth: The relative efficacy of early and deferred vocabulary training, studied by the method of co-twin control. Genetic Psychology Monographs, 8, 209–319. Google Scholar | |
|
Taylor, J., Roehrig, A. D., Soden-Hensler, B. S., Connor, C. M., Schatschneider, C. (2010). Teacher quality moderates the genetic effects on early reading. Science, 328, 512–514. Google Scholar | Crossref | Medline | ISI | |
|
Taylor, J., Schatschneider, C. (2010). Genetic influence on literacy constructs in kindergarten and first grade: Evidence from a diverse twin sample. Behavior Genetics, 40, 591–602. Google Scholar | Crossref | Medline | ISI | |
|
Willcutt, E. G., Pennington, B. F., Duncan, L., Smith, S. D., Keenan, J. M., Wadsworth, S., . . . Olson, R. K. (2010). Understanding the complex etiologies of developmental disorders: Behavioral and molecular genetic approaches. Journal of Developmental & Behavioral Pediatrics, 31, 533–544. Google Scholar | Crossref | Medline | ISI |

