If this market resolves YES https://manifold.markets/Ernie/bridge-built-connecting-mainland-it?r=TmFkaWFNYXRzaXVr I will call the year in which the bridge is finished (defined as the year when the first 100 cars cross it) t, the previous year t-1 and the next year t+1. I will compute (U(t+1) - U(t-1))/U(t) where U is the unemployment from ISTAT (http://dati.istat.it/Index.aspx?QueryId=20744&lang=en) for Sicily and for Italy as a whole. If the result is strictly smaller (with sign) for Sicily I will resolve YES as soon as the data becomes available for year t+1. Otherwise I will resolve NO. What I am trying to measure is the relative change in unemployment.
Example: the bridge is finished in 2029. Unemployment for Sicily in 2028 was 14%, 16% in 2029, and 11% in 2030. Unemployment for Italy in 2028 was 10%, in 2029 8%, and in 2030 9% I will calculate, for Sicily (11 - 14)/16 = -0.1875 and for Italy (9-10)/8 = -0.125 and, since -0.1875 < -0.125 I will resolve YES.
If bridge construction is not started (that market resolves NO) I will resolve N/A.
If ISTAT data becomes unavailable I will attempt to substitute it with some other reliable source or, failing that, also resolve N/A.
If significant territorial changes happen to Italy and/or Sicily that would make the data on unemployment meaningless, I will attempt to track down the unemployment figure corresponding to the territory of Italy and Sicily in 2023 or resolve N/A if I do not manage to.