$ProShares Ultra VIX Short Term Futures(UVXY)$The data is pretty clear that the likelihood of a stock market crash or correction has grown considerably. It's impossible to precisely predict when a crash might occur, how long the decline will last, or how steep the drop could be. But the data strongly suggests that downside is in the offing.

While this might be a disappointing revelation to some investors, it shouldn't be. Crashes and corrections are a normal part of the investing cycle. More importantly, theyprovide an opportunityfor investors to buy into great companies at a discount. Just think about all the great companies you're probably kicking yourself over for not buying last March.

The reason to be excited about crashes and corrections is also found in the data. You see, of those 38 previous corrections in the S&P 500 since the beginning of 1950, each and every one has eventually been put into the rearview mirror by a bull market rally. Plus,at no point over the past centuryhave rolling 20-year total returns (including dividends) for the S&P 500 been negative.

If you need further encouragement to buy during a correction, keep in mind that 24 of the 38 double-digit declines in the S&P 500 havefound their bottom in 104 or fewer calendar days(3.5 months or less). Crashes and corrections may be steep at times but tend to resolve quickly. That's your cue to have cash at the ready in the event that opportunity knocks.