I think its very confusing to call d = 0.2 to 0.5 ‘small’, especially in the context of a 4 day workshop. Imagine the variable is IQ. Then a ‘small’ effect increases iq by 3 to 7.5 points. That boost in iq would be much better described as ‘huge’. However IQ has a relatively large standard deviation compared to its mean (roughly 15 and 100).
Lets look at male height. In the USA male height has a mean around 70 inches and a standard deviation around 4 inches. (Note 4⁄70 is 38% of 15⁄100). A d of 0.2 to 0.5 would correspond to an increase in height of 0.8 to 2 inches. Some people are willing to undergo costly, time consuming and painful length lengthening surgery to gain 4-5 inches of height. If a four day, 4000 dollar workshop gave increased your height by 0.8 to 2 inches millions of men would be on the waiting list. I know I would be. That doesnt really sound ‘small’ to me.
IQ has a relatively large standard deviation compared to its mean
No, the mean here is an arbitrary convention, so 15 and 100 don’t tell us anything relevant. The appropriate comparison is to what other interventions have accomplished.
I think its very confusing to call d = 0.2 to 0.5 ‘small’, especially in the context of a 4 day workshop. Imagine the variable is IQ. Then a ‘small’ effect increases iq by 3 to 7.5 points. That boost in iq would be much better described as ‘huge’. However IQ has a relatively large standard deviation compared to its mean (roughly 15 and 100).
Lets look at male height. In the USA male height has a mean around 70 inches and a standard deviation around 4 inches. (Note 4⁄70 is 38% of 15⁄100). A d of 0.2 to 0.5 would correspond to an increase in height of 0.8 to 2 inches. Some people are willing to undergo costly, time consuming and painful length lengthening surgery to gain 4-5 inches of height. If a four day, 4000 dollar workshop gave increased your height by 0.8 to 2 inches millions of men would be on the waiting list. I know I would be. That doesnt really sound ‘small’ to me.
No, the mean here is an arbitrary convention, so 15 and 100 don’t tell us anything relevant. The appropriate comparison is to what other interventions have accomplished.