Maybe I was too sloppy in my usage. But what I *meant* to say still applies. The larger the sample, the smaller the effect size that can be detected to be statistically significant. So with extremely large samples, extremely small effect sizes can be detected to be statistically significant. But it is not automatically true that small effect sizes due to large samples are not meaningful, they can be very meaningful. So, people may laugh at you if you say "Hey, I accounted for 1% of the variance!" But pragmatically, accounting for 1% of the variance may benefit millions of peoples lives in America alone.
wedj On 8/16/04 4:38 PM, "Paul Okami" <[EMAIL PROTECTED]> wrote: > Small effect sizes in large populations are not the same as statistical > significance due to large samples. This is what I was referring to. > > Paul Okami > ----- Original Message ----- > From: "Wallace Dixon" <[EMAIL PROTECTED]> > To: "Teaching in the Psychological Sciences" <[EMAIL PROTECTED]> > Sent: Monday, August 16, 2004 12:56 PM > Subject: Re: teaching effect size > > >> But you have to be careful about this. As noted by Rosenthal, small > effects >> sizes in large populations do not mean unimportant. Effect sizes as small >> as 1% can still translate into an influence on millions of people in the > US, >> as was the case in the aspirin study and the decreased rate of second > heart >> attacks. >> >> Wally Dixon >> >> >> >> >> On 8/16/04 12:25 PM, "Paul Okami" <[EMAIL PROTECTED]> wrote: >> >>> I usually give an example of results that are statistically significant >>> because of large samples, but have little meaning in the real world. In >>> other words, they're "real" but "not important." >>> >>> That makes it easy to talk about a statistic that reflects magnitude of >>> group differences. It's really very intuitive. (I don't discuss the > math >>> involved). >>> >>> Paul Okami >>> ----- Original Message ----- >>> From: "Hatcher, Joe" <[EMAIL PROTECTED]> >>> To: "Teaching in the Psychological Sciences" <[EMAIL PROTECTED]> >>> Sent: Monday, August 16, 2004 12:18 PM >>> Subject: teaching effect size >>> >>> >>>> Hi Tipsters, >>>> >>>> I apologize for the cross-posting. >>>> >>>> I teach the first semester of our two-semester Research Design and >>>> Statistics class, my part of which goes through t-tests and requires a >>>> completed project. When I first started teaching the course, "effect >>> size" >>>> wasn't one of the topics covered. In trying to update the class, I > would >>>> like to teach this concept, but I'm having some trouble, as it doesn't >>> come >>>> as naturally to me as do some of the other topics, and most of the >>>> explanations of effect size seem very complicated. >>>> Can someone point me to a method to teach effect size that is >>> easily >>>> understood by undergraduates? >>>> >>>> Joe Hatcher >>>> Ripon College >>>> Ripon, WI >>>> [EMAIL PROTECTED] >>>> >>>> >>>> >>>> Joe W. Hatcher, Jr., Ph.D. >>>> Psychology >>>> Ripon College >>>> Ripon, WI 54971 >>>> USA >>>> [EMAIL PROTECTED] >>>> >>>> --- >>>> You are currently subscribed to tips as: [EMAIL PROTECTED] >>>> To unsubscribe send a blank email to >>> [EMAIL PROTECTED] >>>> >>> >>> >>> >>> --- >>> You are currently subscribed to tips as: [EMAIL PROTECTED] >>> To unsubscribe send a blank email to > [EMAIL PROTECTED] >>> >> >> >> -------------------------------------------------------------------------- > -- >> Wallace E. Dixon, Jr. | >> Chair and Associate Professor | If children grew up according to >> of Psychology | early indications, we should have >> Department of Psychology | nothing but geniuses. >> East Tennessee State University | -Johann Wolfgang von Goethe >> Johnson City, TN 36714 | >> (423) 439-6656 | >> -------------------------------------------------------------------------- > -- >> >> >> >> >> --- >> You are currently subscribed to tips as: [EMAIL PROTECTED] >> To unsubscribe send a blank email to > [EMAIL PROTECTED] >> > > > > --- > You are currently subscribed to tips as: [EMAIL PROTECTED] > To unsubscribe send a blank email to [EMAIL PROTECTED] > ---------------------------------------------------------------------------- Wallace E. Dixon, Jr. | Chair and Associate Professor | "When I turned two I was really of Psychology | anxious because I'd doubled my Department of Psychology | age in a year." East Tennessee State University | -Steven Wright Johnson City, TN 36714 | (423) 439-6656 | ---------------------------------------------------------------------------- --- You are currently subscribed to tips as: [EMAIL PROTECTED] To unsubscribe send a blank email to [EMAIL PROTECTED]
