In a picture of the normal distribution, the baseline is usually marked off with numbers. The centered baseline number is the mean score. Other baseline numbers, to the right and to the left of the mean, typically correspond to scores that lie 1, 2, and 3 standard deviations away from the mean. If the picture were to show the scores positioned .6745 of a SD to right and left of the mean, we’d see the upper and lower quartile points, respectively. These points correspond to the 75th and 25th percentile points.