Roger G. Ibbotson Quotes

We can extrapolate from the study that for the long term individual investor who maintains a consistent asset allocation and leans toward index funds, asset allocation determines about 100% of performance.

On average, 90 percent of the variability of returns and 100 percent of the absolute level of return is explained by asset allocation.

That what's most relevant to you is whether and how you're doing something different from what everybody else is doing.