NEW YORK ( TheStreet) -- There's no shortage of Black Friday sales data out Monday, and as usual the reports are overly optimistic. But if history is any indication, preliminary data points don't paint an accurate picture of the total holiday season.

The National Retail Federation reported a 16% jump in total Black Friday sales to $52.4 billion. The research firm estimated 226 consumers flocked to stores and shopped online and the average holiday shopper spent $398.62 during the weekend, up from $365.34 last year.

But these data points are compiled from a survey of 3,826 consumers regarding how they plan to spend with a margin error of plus or minus 1.6%.

ShopperTrak, a Chicago-based research firm, claimed Black Friday sales grew 6.6% to $11.4 billion, while foot traffic rose 5.1%.

The research firm gets its information via equipment installed in stores to measure traffic, not exactly the most accurate picture of the total strength of the retail space.

Both of these surveys, and dozens of others, vary wildly, mostly because they each use different methodologies. Some track just in-store data, while others measure online sales.

"NRF and ShopperTrak reports are interesting data points, but do not correspond well with ultimate outcomes for the holiday season," Goldman Sachs analyst Matthew Fasslet wrote in a note. "We are grateful that multiple third-parties provide color on Black Friday sales, but the reality is that few of these metrics align well with actual outcomes for the overall holiday season."

Instead, Fassler said to focus on year-to-date core retail sales, which tend to be a better leading indicator of holiday season sales than any Black Friday metric.

"'Core' retail sales growth in November and December typically tracks in-line with growth posted in the January to October time frame," Fassler wrote. "Over the past 10 years, excluding the years impacted by the financial crisis (2008-2009), the average gap between these two growth measures was 0.1%, with a standard deviation of 1% and the largest gap at 1.8 percentage points in 2000."

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