Mark Duggan, Steven D. Levitt; AMERICAN ECONOMIC REVIEW VOL. 92, NO. 5, pp. 1594-1605 http://pricetheory.uchicago.edu/levitt/Papers/DugganLevitt2002.pdf
{return (x - newdata[j, -1])} result <- apply(df[, -1], 1, minus) r = c() for (i in 1:4967) { r = c(r, sum(as.data.frame(result[i]) == 0)) } print(df[which.max(r),1]) }