=+American Statistician [1999]: 298–302). (The investigators who wrote the article analyzed data from a particular year. For a sensible choice of class intervals, the histogram did not look at all normal, but after further investigations the researchers determined that this was due to some hospitals measuring weight in grams and others measuring to the nearest ounce and then converting to grams. A modified choice of class intervals that allowed for this measurement difference gave a histogram that was well described by a normal distribution.)