Average Household Income Estimation

I've noticed that the average household income for Arkansas keeps increasing each year, but it seems way too high. I was hoping someone could shed some light on how this is calculated and why it differs so much from census data. I estimated the model using Econometric RPC method and built through multipliers. Below I've included IMPLAN's estimate for the 2010 data year and the estimate from the census bureau's American Community Survey (ACS). Thanks for any info you can provide! AR 2010: IMPLAN $82,725 ------- ACS $52,382