Lewm- Agree completely that correlation does not say anything about causation but remember we were trying to identify factor potentially responsible for differences between carts of same basic architecture; presumably w same cantilevers, stylus, body, etc. Diff btwn MI, MM, and MC carts have so many variables, IMO, that they are unlikely to be explained by one parameter. Not said too clearly; it's the end of a long day, but I think you know what I mean. BTW, since my primary source is (shudder) a music server, I was trying to point out that I do not have the experiential "database" to apply to the question that either you or Doug have. Apologies to the OP for taking this so far off-course.