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April 17, 2009


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YAY! You did post it! Thank you so much for once again using all your scientific training and your best persuasive writing to debunk these toxic myths that these women in the media keep putting out there! What a level headed breath of fresh air! I'll be linking to you soon.

Beautifully done. thanks for the deep thinking and the clear writing. Please send to the NYT and the Atlantic Monthly. ASAP!

Thank you!

Love it, Jamie!!

I've been waiting to read your response. Thank you!

Because of that randomization, his work is untroubled by the problems that plague observational studies.

Do you really think this? Wow. No, just no. It alleviated some of the confounding issue, but hardly all of them, and certainly not the ones that most people think are the driving factors.

I am editing this comment a few weeks later to clarify a couple of things. I considered writing about the covariate question in this post, but I decided not to given the length of the post and its intended audience. Kramer assessed for between-groups differences in maternal and paternal education and didn't find anything significant. It is certainly possible that factors other than the intervention Kramer was studying explain the cognitive outcomes he described. It seems more plausible to me, however, that Kramer's conclusions are correct: breastfeeding plays a part in cognitive development. The remainder of this comment is my original reply to Karen, whose comment appears immediately above this one.

"Untroubled" is too sweeping, but the scale of the issue is much, much smaller in a randomized study than in an observational study. What concerns do you have about Kramer's approach to covariate control? It's not as if he ignored the issue.

I also haven't seen published responses taking Kramer to task for any failure to address important confounding variables. Der & colleagues wrote in, unsurprisingly, but I think their focus was more on the difficulties of assessing cognition in a multilingual population. I hope you'll write to the editor if you think Kramer has overlooked something important.

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