Textbooks make claims like:
“Dixon [et al] studied 361 siblings belonging to large families and found that younger siblings were significantly more extraverted in terms of sociability compared to older siblings.”
Should we believe them? I look at:
Dixon, Reyes, Leppert, & Pappas (2008). Personality and birth order in large families. Personality and Individual Differences, 44(1), 119–128.