Classify the variable as nominal-level, ordinal-level, interval-level, or ratio-level measurement. Leap years: \( \ldots 2008,2012,2016, \ldots \) Ordinal Interval Ratio Nominal

Leap years can be classified as interval-level measurement. This is because the years are measured on a scale where the intervals between them are meaningful and consistent, but there is no true zero point. For instance, the difference between 2008 and 2012 is the same as the difference between 2012 and 2016, but we cannot say that one year is "twice" another in a meaningful way. In the context of leap years, it's interesting to note that these intervals are part of a larger systematic pattern in the Gregorian calendar. Leap years occur every four years, but with exceptions, like not every century year unless divisible by 400. This systematic approach ensures that our calendar stays aligned with the Earth’s revolutions around the Sun.