Fig. 4

IDW interpolation of average brucellosis incidence between 2004 and 2017 in mainland China. Inverse distance weighting (IDW) estimates the unknown values of the unmeasured points using the weighted average method, which calculates the weight of the unknown points based on their distances to known points. The closer the unknown points are to the known points, the more influence the known will have on the unknown points. The average brucellosis incidence decreased from the north to south between 2004 and 2017. Inner Mongolia was most affected by brucellosis