FORTUNE — Venture capitalists cut back on new deals last quarter, according to new data from Dow Jones VentureSource.

Approximately $6 billion was raised by 752 U.S.-based companies, which represented an 11% dollar decrease over both Q4 2012 and Q1 2012. Lower figures were seen all over, including for all deals stages (seed, expansion, etc.) and for most industry sectors (including IT and healthcare). Bad news for entrepreneurs, but first quarters are often a bit hinky due to the prior rush of year-end transactions.

What really jumped out, however, was the data on deal valuations. Check out this chart:

Source: Dow Jones VentureSource

What that shows is a whopping 79% decrease in median pre-money valuations between Q4 2012 and Q1 2013. Not an average that might have been skewed by a giant deal or two, but a median.

To be sure, Dow Jones does not receive valuation data on all of its deals (or even a majority, I’d assume) — but this sort of volatility is unprecedented. Maryam Haque, a VentureSource senior research analyst, offered up the following via email:

Valuations are a very difficult data point to capture because not all companies report this sensitive data. Also, keep in mind the data in the quarterly report is very top line and does not dive deeper into the trend by industry, round class, or development stage. The number of deals reporting a pre-money valuation for 1Q’13 was pretty consistent with the past 4 quarters. We’re always capturing new data as it becomes available, so the $6.05 million median value will most likely change, accordingly, going forward.

Basically a big fat “dunno,” with expectation that the dip won’t look quite so severe when additional information comes in. Should be interesting to see what the National Venture Capital Association reports tomorrow morning, with its quarterly MoneyTree report. It is worth noting that PitchBook found the following for Q1:

So right now I’ll chalk the VentureSource valuation data up to some statistical anomaly. Unless MoneyTree looks similar tomorrow, at which point we’d really have something to talk about.

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