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Title: Birth Order Has No Effect on Intelligence: A Reply and Extension of Previous Findings
Resulting in 1 citation.
1. Wichman, Aaron L.
Rodgers, Joseph Lee
MacCallum, Robert C.
Birth Order Has No Effect on Intelligence: A Reply and Extension of Previous Findings
Personality and Social Psychology Bulletin 33,9 (September 2007): 1195-1200
Cohort(s): Children of the NLSY79
Publisher: Society for Personality and Social Psychology
Keyword(s): Age at First Birth; Armed Forces Qualifications Test (AFQT); Birth Order; Digit Span (also see Memory for Digit Span - WISC); I.Q.; Intelligence; Modeling, Multilevel

Permission to reprint the abstract has not been received from the publisher.

We address points raised by Zajonc and Sulloway, who reject findings showing that birth order has no effect on intelligence. Many objections to findings of null birth-order results seem to stem from a misunderstanding of the difference between study designs where birth order is confounded with true causal influences on intelligence across families and designs that control for some of these influences. We discuss some of the consequences of not appreciating the nature of this difference. When between-family confounds are controlled using appropriate study designs and techniques such as multilevel modeling, birth order is shown not to influence intelligence. We conclude with an empirical investigation of the replicability and generalizability of this approach.
Bibliography Citation
Wichman, Aaron L., Joseph Lee Rodgers and Robert C. MacCallum. "Birth Order Has No Effect on Intelligence: A Reply and Extension of Previous Findings." Personality and Social Psychology Bulletin 33,9 (September 2007): 1195-1200.