Dow up 10 straight days: So what?

Traders work on the floor of the stock exchange, March 14, 2013 in New York City. / Allison Joyce/Getty Images

(MoneyWatch) By now, you probably know the Dow Jones industrial average is at an all-time high and just logged it's tenth up day in a row. This hasn't happened since 1996, when the dot-com bubble was still a youngster.

It's easy to get caught up in the emotions of it all, but investing based on data usually works out much better. To see how statistically meaningful this 10 day streak is, I contacted S&P Dow Jones Indices and cranked out some simple MS Excel calculations. 

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According to the folks at S&P Dow Jones Indexes, the Dow rises 52 percent of days and declines the other 48 percent of the time.  By my calculations, we should have 10 up days in a row roughly every two years and nine months. By this measure, this 10 day winning streak was way statistically overdue.

Next I looked at the magnitude of the 10 day run. Over that period, the Dow increased 3.4 percent. That amounts to only about 0.34 percent each day. Meanwhile, it's worth noting that the U.S. stock market didn't rise for 10 straight days -- the Wilshire 5000 and even the narrower S&P 500 declined on March 12.

Before you leap to the conclusion that this is statistical proof that investors are bullish, consider that the real statistical oddball wasn't reported -- the fact that this latest streak took six times longer to occur than statistics would have predicted.

The fact that the 30 stocks in the Dow, not even weighted by their values, gained for 10 days in row doesn't tell us a thing about the market going forward. What it does tell us is that humans are great at finding patterns out of randomness and that those patterns make news. 

Signal or noise?  Easy call: noise. Yet this noise makes us all feel better.

[Tank_Commander]

Gambling is still gambling. It doesn't matter if its your own money or what the banks are doing with someone Else's. The house always wins. Saying it's either democrat or republican that's benefiting is baloney. The only beneficiaries are the banks, all the other "little people" are simply getting a small taste of what they are making with the money that isn't theirs to begin with. http://www.youtube.com/watch?v=x0k2PmF-o5Q

[Allan_Roth]

TANK_COMMANDER,

Any investor willing to "minimize expenses and emotions and maximize diversification and discipline" doubled their money in the past ten years. Again, this worked for Republicans, Democrats, and everyone else.

http://www.cbsnews.com/8301-505123_162-57562741/a-dare-to-de-dull-decade-of-investing/

[Allan_Roth]

RETIREDARMY_NURSE,

I make it a point not to do political commentary. I will address your comment that your 401Ks have only returned to 1999-2000 levels. I'm showing that a 60% stock 40% bond portfolio of low cost index funds rebalanced every six months is up over 80%. Few got that return due to expenses and emotions that happen to target Democrats, Republicans, and everyone else.

[w_roos]

Still down from the record in 2007 after adjusting for inflation. Plus, the market has been crappy in general since 2000. Sorry, I'm not that excuberrant, rationally or irrationally.

[Allan_Roth]

W_Roos,

Not true. The total return of the total stock market (as measured by Vanguard Total Stock Index Fund VTI) is up 15.7% from October 9, 2007, the pre-crash high. That did beat inflation. A balanced portfolio did even better.

Both require minimizing emotions.

[opedanderson2]

Oh man.

Youre shilling for Obama knows no bounds.

Of course it's a big deal!!!! But because it might have NOTHING to do with your guy, you continue to cover for him......

[Allan_Roth]

OPEDANDERSON2,

Please educate me. What in my piece had relevance to Obama or even politics?

[dashed_out]

I don't think the Dow has anything to do with anything. It just has to do with how much or how little money there is being invested. It's really a miracle it hasn't crashed before now, what with everything going on in the Middle East and here at home.

[Allan_Roth]

You sound like you think you are smarter than the market. There is a ton of data that shows this doesn't work. One key in investing is knowing we don't know.

[bobnjersey]

[I don't think the Dow has anything to do with anything. It just has to do with how much or how little money there is being invested.]
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so then ... what does 'how much or little people are investing' have to do with anything?

doesn't that relate to how much or how little people are spending?

what do these things say about the 'psychology of economics' ... the self fulfilling 'belief' that if things are good ... people invest and spend ... which makes things economically 'good' ... and if they 'believe' things are bad ... people pull back on investment and spending ... which slows economic activity ... thereby making things bad.

maybe nothing has anything to do w/ anything ... or maybe everything has something to do w/ everything else.