by David Firth
Question: What are the most important variables in regression?
Important for what? Without a criterion for importance, the inquiries are meaningless.' Goes on to distinguish three notions of importance, namely :
- `theoretical importance' (measured by βΧ)
- `level importance' (measured by βΧ * μΧ )
- `dispersion importance' (measured by σΥ / βΧ* σΧ
Of the last, Achen says: `although almost no one is substantively interested in it, many social scientists use it as their sole importance measure.' He suggests standardization by the (supposed fixed) range of a variable, rather than by its s.d., to achieve comparability across samples.