Should we only focus on influences with high effects sizes and leave out the low ones?

It has been emphasized for the readers of the research that it is the interpretations of the effect sizes that are important and the league was primarily used as an organizer.  There are many intriguing influences that John Hattie has continued to research and publish.  This is particularly the case where some effects are low. For example, the effects of class-size are much lower (but note they are still positive) than many have argued. Further, in some cases small effects can be valuable as they can indicate that the intervention is moving in the right direction. They can also indicate that some deeper processes may be changing, and they can indicate that more time, implementation press, or adjustment is needed. Therefore, just because an effect is not >0.4 does not mean it is not worthwhile.

In relation to high effect sizes is the influence of feedback, which continues to be an area of research for the VL team. Feedback is among the highest but also most variable effects, for example, while much feedback is positive much is also negative. Feedback is an effect where the variance is critical.  While this variance can be understood research continues to understand the important moderators and influences relating to feedback.  For example, it is critical to distinguish between giving and receiving feedback, between “how am I going” and “where the next” feedback, and the feedback effects from students to teachers.  More research will be published on feedback from Professor John Hattie and the VL team on the intricacy of this influence.

This has been explored at length and readers are encouraged to:

• Accept the evidence that the effects are small
• Understand the reasons that they are small (see Hattie, J (2007). The paradox of reducing class size and improved learning outcomes. International Journal of Education, 42, 387-425).