I've had a read of this paper. Colen, C.G., Ramey, D.M., Is Breast Truly Best? Estimating the Effects of Breastfeeding on Long-term Child Health and Wellbeing in the United States Using Sibling Comparisons, Social Science & Medicine (2014), doi: 10.1016/j.socscimed.2014.01.027. It's a worthwhile topic - take siblings who differ in how they were fed as infants, and see how the long term outcomes compare. But I do think it's badly executed. The statistical presentation is mystifying. The authors need to read Ben Goldacre's book Bad Science which has a useful chapter on making findings intelligible. Having said that, the exercise is a constrained by 2 major facts: * the bf info is restricted to ever breastfed, and how long with any breastfeeding in weeks ie no information on whether the bf was exclusive, predominant, minimal... * the outcomes are selected from a longitudinal cohort study of children aged between 4 and 14 and are body mass index, obesity, asthma, hyperactivity, parental attachment, behavioral compliance, reading comprehension, vocabulary recognition, math ability, memory based intelligence, and scholastic competence That list is a strange one. Who of us on this list would expect to see a difference in BMI/obesity because of any breastfeeding lasting into the early teens - family influence (obviously strong, for siblings) and other environmental influences would overwhelm any 'breastfeeding factor'. Has anyone even hypothesised that hyperactivty (defined how? As ADHD?) is affected by any breastfeeding? Behavioural compliance? What's that on the list for? The sample is reduced to 1,773 children by the time the cohort is reduced to 'discordant siblings' - I would be unsure if the survey is powered enough to reveal significant findings, anyway. Not impressed. Heather Welford Neil NCT bfc, tutor, UK -- *********************************************** Archives: http://community.lsoft.com/archives/LACTNET.html To reach list owners: [log in to unmask] Mail all list management commands to: [log in to unmask] COMMANDS: 1. To temporarily stop your subscription write in the body of an email: set lactnet nomail 2. To start it again: set lactnet mail 3. To unsubscribe: unsubscribe lactnet 4. To get a comprehensive list of rules and directions: get lactnet welcome