What is the best theoretical/methodological fit of social position (broadly defined socioeconomic factors or life chances: education, occupational prestige, income, health insurance) within our planned international cancer outcome comparative studies?

And

Is it possible that previous general population comparisons in this field were misleading?

Given the great diversity of both Canadian and American populations (diverse people living in diverse places), we thought it likely that such gross, general population comparisons had missed many more specific, and potentially more policy-interesting analytic opportunities.

And

We thought it likely that any effect of country would be moderated by social position (e.g., by the ability to pay in the US).