Inter-annual variability of spring wheat yield, from left to right, at the Census Agricultural Region, Ecodistrict, and Rural Municipality scales for the Canadian Prairie provinces (i.e. Alberta, Saskatchewan, Manitoba). The boxes represent the first and third quartiles as a measure of data spread spanning 50% of the dataset and eliminating the influence of outliers; the median yield is the horizontal line within the box. The whiskers are the two lines outside the box that extend to the highest and lowest data values. n is the total number of spatial units. Note: some ecodistricts overlay two provinces as they are not linked to administrative boundaries.