For the time periods we can observe, we find that the intra-portfolio correlation is, by and large, less the longer the period of time for which we have observations.
"There's been a near-perfect correlation in equities gains each time the Fed induced more liquidity into the marketplace, " said Mark Luschini, chief investment strategist at Janney Montgomery Scott.
In spite of dramatic differences in the rates of the four cancers by race and sex, as well as dramatic changes over the 35-year time period, there was little evidence of a correlation between prevalence of mentholated cigarette use and cancer rates.
State licensing laws mindlessly emphasize time spent -- usually years -- taking teacher-education courses, yet there is little correlation between certification requirements and effectiveness in the classroom.