The variance of the population was 5.50 s, so in a normal distribution, 95.4% of the data would lie between -11.34 s and 10.68 s, from (mean -2  variance) to (mean + 2  variance). The skewed t-distribution approximation gave the range of -10.33 s to 8.76 s for 95.4% of the errors, thus suggesting a 15% smaller range (highlighted in light pink in Figure ). In fact, 95.2% of the actual errors fell within this range, thus making the skewed t-distribution a good option for estimating RT prediction risks. The size of this range is 22.02 s, or 12.2% of the LC method scale (120 s).