YearYear of measurement (surrogate for variety improvements)
 
    Rain0Pre-season rainfall (in.)
 
    Temp1Mean temperature for the first growing month (deg. F)
 
    Rain1Rainfall for the first growing month (in.)
 
    Temp2Mean temperature for the second growing month (deg. F)
 
    Rain2Rainfall for the second growing month (in.)
 
    Temp3Mean temperature for the third growing month (deg. F)
 
    Rain3Rainfall for the third growing month (in.)
 
    Temp4Mean temperature for the harvest month (deg. F)
 
    YieldYield of wheat in Iowa for the given year (bush./acre)