with the July seasonal adjustment factor routinely subtracting a substantial amount from the NSA number, averaging at -$5.2 billion, in 2012, for the first time this decade, the seasonal adjustment not only did not subtract, but in fact added "value" to the NSA number, resulting in a seasonally adjusted number that was $1.9 billion higher than the NSA number at $403.9 billion.
So what would have happened if instead of arbitrarily deciding to add a seasonal contribution for the first time in a decade, the Census Bureau had used the last decade average factor of $5.2 billion (not adjusted for inflation, so the end number would be far greater)? Instead of rising by 0.8% Seasonally Adjusted retail sales would have declined from $400.7 billion to $395.5 billion, or a 1.3% decline.
And that is how data is fudged.