I was talking to my parents this weekend about investing (fraught with peril, but I think it turned out ok). I told them that I thought their actively managed funds were costing them ~1% more than an index fund would (plus trading costs), so they should switch. My dad said, "but that assumes the manager can't do better. This guy has beaten the averages since we owned it." I told him there's piles of evidence that supports good theoretical reasons to believe managed funds don't beat the averages in the long run, and I'd like to show him a nice summary of some of the evidence that is out there. I've read this same message a zillion places, and I'd like to find one of the most persuasive summaries that is short enough he might read it. Any suggestions?