 Importantly, most scientific research needs only to discern patterns across large numbers of individuals—to take an easy case, determining whether widows tend to be less happy than newlyweds—and this is compatible with substantial unreliability in assessing individual happiness. Similarly, an inaccurate thermometer might be a poor guide to the temperature, but readings from many such thermometers could correlate fairly well with actual temperatures—telling us, for instance, that Minnesota is colder than Florida.