Perhaps a combination of i) different degrees of intensity of engagement and ii) changing methodology.
1 - The degree of high-intensity engagement (reading and writing intellectual arguments) is meant to be much harder to grow than total people who affiliate with EA.
2 - How did the Survey methodology change between years?
Perhaps a combination of i) different degrees of intensity of engagement and ii) changing methodology.
1 - The degree of high-intensity engagement (reading and writing intellectual arguments) is meant to be much harder to grow than total people who affiliate with EA.
2 - How did the Survey methodology change between years?