Study this table of temperatures for 3 U.S. cities.
Maximum Temperature Means (Fahrenheit)
January July Yearly Mean Fairbanks, AK -1.6 72.3 36.5 Phoenix, AZ 65.9 105.9 85.9 Honolulu, HI 80.1 87.5 84.4
- The annual maximum temperature mean for Fairbanks, Alaska is 36.5, but it is a balmy 72.3 degrees in July.
- The mean for Phoenix, Arizona is 85.9, yet it is a cool 65.9 in January.
- The mean is a poor predictor in these 2 cities, but in Honolulu, Hawaii the mean of 84.4 is typical of temperatures year round.
It needs a second statistic, the standard deviation, to make sense of these contradictions
Why We Need It
Calculating It and