A meta-analysis of writing instruction for adolescent students. - Graham, S; Perin, D (2007)
meta-analysis; evidence grade C

A Meta-Analysis of Writing Instruction for Students in the Elementary Grades. - Graham, S; McKeown, D; Kiuhara, S; Harris, KR (2012)
meta-analysis; evidence grade C

Teaching children to write: A meta-analysis of writing intervention research - Koster, M; Tribushinina, E; de Jong, PF; van den Bergh, H (2015)
meta-analysis; evidence grade C

Writing instruction improves students’ writing skills differentially depending on focal instruction and children: A meta-analysis for primary grade students - Kim, YSG; Yang, D; Reyes, M; Connor, C (2021)
meta-analysis; evidence grade C

A Quantitative Synthesis of Research on Writing Approaches in Grades 2 to 12. Best Evidence Encyclopedia (BEE) - Slavin, RE; Lake, C; Inns, A; Baye, A; Dachet, D; Haslam, J (2019)
meta-analysis; evidence grade B

Improving Writing Quality: Evaluation Report and Executive Summary - Torgerson, D; Torgerson, C; Ainsworth, H; Buckley, H; Heaps, C; Hewitt, C; Mitchell, N (2014)
rct; evidence grade B

Calderdale Excellence Partnership: IPEELL. Evaluation report and executive summary - Torgerson, CJ; Ainsworth, H; Bell, K; Elliott, L; Fountain, I; Gascoine, L; Hewitt, CE; Kasim, A; Kokotsaki, D; Torgerson, DJ (2018)
rct; evidence grade B

Genetic and environmental influences on writing and their relations to language and reading - Olson, RK; Hulslander, J; Christopher, M; Keenan, JM; Wadsworth, SJ; Willcutt, EG; Pennington, BF; DeFries, JC (2013)
twin-adoption; evidence grade B