I suspect that the opposite is far more often the case: Statistically significant results due only to the fact that large samples were used represent lack of clinical significance or meaningful group differences.
Paul ----- Original Message ----- From: "Wallace Dixon" <[EMAIL PROTECTED]> To: "Teaching in the Psychological Sciences" <[EMAIL PROTECTED]> Sent: Monday, August 16, 2004 5:17 PM Subject: Re: teaching effect size > 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] > --- You are currently subscribed to tips as: [EMAIL PROTECTED] To unsubscribe send a blank email to [EMAIL PROTECTED]
