Regression dilution. The circles denote the data from SG, and the black, solid line is the ordinary least-squares fit to that data. The x-intercept of this line (about 9.5 billion years), is the estimate for the age of life according to SG. The region between the black, dashed curves is the 95% prediction interval for the fit. The red, solid line is the least-squares fit according to a measurement error model with λ = 1.14; the red, dashed curves outline the 95% prediction interval/region. Note that this region includes 4.5 billion years (i.e., the Earth’s age).