Nothing.
Seriously.
Nothing. Nothing by commenters on
either blog where the original analysis and reactions is prominently mentioned
(Weisenthal and Krugman). Nothing by the
bloggers themselves. No change in the analysis as presented on the blog. Dead silence. Debate continues to be waged
based on the uncorrected blog data.
I have racked my brain as to why this might be. The best reason I can think of is that most
people are so focused on the “bright” parts of the data as presented, the fact
that the two measures over time involved show a clear relationship, that they
ignore the fact that one of the two measures is not quite the correct one to
use. It is, if you will, an example of
blindness like the blindness caused by trying to look ahead into a landscape of
snow reflecting the sun fiercely – the well-known phenomenon of “snow
blindness.” Data snow blindness. And, as in the case the other snow blindness,
you become truly blind – you simply don’t notice the information indicating
that the analysis is off.
The Story
The story begins when Weisenthal reacts to an ongoing debate
on the merits of investment in gold by doing a couple of graphs comparing the
value of the S&P 500 index over time (1979 and 2007 to now) to the value of
gold in the markets ($/troy ounce). His point – a valid one – is that even with
recent fluctuations in gold’s price, investment in stocks outperforms
investment in gold over time.
Now, as I found out in doing my post-MIT-Sloan-School-of-Management
research on investment theory for my own use, it turns out that the S&P 500
is a price-only measure. That is, the
typical value of the S&P 500 that everyone quotes does not include the
value of dividends that the companies issue over time, and it doesn’t include
the reinvestment of those dividends. As
far as I can tell from observations over the past 15 years as well as from
previous data, the dividends themselves average about 2.3% per year, and the
reinvestment adds another 0.1% per year (the “geometric mean” of returns, the
correct way to measure, suggests that at least until about 2007 (a period of
maybe 90 years), the growth in the S&P 500 was about 10.8% per year, which
meant that reinvestment of dividends over the course of a year would yield about
2.3% times 10.8% times ½ [to reflect the fact that dividends don’t all occur at
the start of the year], or about 0.12%).
If you don’t believe my assessment, go look at the S&P
web page where they report S&P 500 values and returns over time. Above the regular report is a measure of “total
return.” If you look at the description
of that return, you find that “total return” does indeed compute return with
dividends included (it appears that dividend reinvestment is also included, but
I’m not sure about that). They do it
over a much longer period than a year, so at this point the TR index is almost
twice the regular S&P 500 index.
If you add in this adjustment, the result of the analysis
changes significantly. In Weisenthal’s
original graph (made so that 2013 represents 1), the ratio of S&P 500 to
gold price goes from about 0.1 in 1979 to 1 in 2013. Accepting the same
starting point, my computed ratio goes from about 0.1 in 1979 to 2.12 in
2013. A sharp drop in the ratio
(reflecting dubious “flight to safety”) from 2007 to 2009 becomes a drop from
about 6 to 2, not a drop from 5 to 0.7. It hasn’t been flat or dropping since
then; it’s been climbing by about 6%.
Stocks don’t just beat gold over long periods of time – they beat gold
over the short and medium term pretty consistently, and over the long term by a
huge amount – try 21.2 times as much.
So I posted this in a comment in Weisenthal’s blog and,
getting no response, in Krugman’s blog.
As noted, no one took notice (I would have posted my comments in caps,
but it’s not netiquette to scream). In
fact, the debate in the comments proceeded as if the original Weisenthal graphs
were the issue – is the government understating inflation data (from “gold bugs”)
and therefore there is another gold price surge to come once that becomes clear? Is the advantage of stocks over gold clear
enough, or would an even further surge erase it?
Data snow blindness.
Implications For Y’All
At this point, I have to distinguish this from other sources
of problematic analyses that have happened recently – e.g., the Reinhart-Rogoff
controversy in economics (which apparently revolved partly around a coding
error) and the London-trader miscomputation of risk (partially a human Excel
miscalculation). Those are not really a
problem of not noticing that one of your sets of data points is not capturing
well what you want it to capture – and they have been exhaustively investigated
and debated.
For another example of data snow blindness, I’d like to go
back to investments again – the idea of 401(k)s (also applicable to IRAs). What no one seems to be pointing out is that
the expense ratios in those 401(k)s are quite high – I believe they’re still above
2%. If your employer isn’t paying into
your 401(k), this means that you must balance the gain 20 years from now in
lower taxes when you cash them out with the loss you get from not sticking an
equivalent amount in a Vanguard S&P 500 index fund with an expense ratio of
0.1%. Even if you pay zero taxes when
you cash out, somewhere over a 10-20-year dividing line, you may well lose
money on your IRA/401(k) compared to the alternative. And that’s true of 401(k) bond investments as
well (vs. bond index funds). Or so the data suggests – but no one seems to
notice this enough to discuss it.
Here’s a few more: stock risk vs. bonds and everything
else. If you have your money in a US S&P 500 index fund, what is your
risk? Over any 20-year period, the stock
market as a whole has outperformed any other investment – including inflation. But what if the stock market collapses
drastically and stays collapsed? If you
think about it, that would mean that the US government has collapsed, since it’s
the government that insures the banks underpinning economic investment by
various mechanisms. So the risk of collapse of the stock market’s 500 largest
members is pretty much the same as the risk of the US collapsing – in which
case, without that government backing, your money is likely to be worthless
(and your gold coins). So why are you “diversifying” beyond the stock market,
again? If you’re planning to start
drawing it down or keeping it level within the next 20 years, then some amount
of, say, a bond index fund or inflation-protected securities (TIPS) that will
keep up with inflation is fine; but the reason for doing anything beyond that
is not as clear as it might seem. Data
snow blindness.
How about stock investment
returns? Today mutual fund companies compare their results to the S&P
500 – is that the regular S&P 500 or the total return one? Do they include their expense ratios – above 2%
until recently, now (afaik) around 1.5% -- and do you compare them to the
Vanguard 0.1% and the Fidelity Spartan 0.2% (plus withholding a bit in cash,
which right now earns effectively zero)?
There’s a reason why those index funds outperform around 70% of all other
stock investments over a 10-year period, and probably close to 90% over a
30-year-period.
In other words, the real implication of data snow blindness
is that it is probably hitting you right in the wallet right now – not
necessarily yours, since everyone else seems to be doing it too. Or almost
everyone else … Gee, I wonder why the Vanguard S&P 500 index fund is one of
the two most popular stock investments today?
Anyway, please think about it. Me, I’m going to go off and check myself for
further signs of data snow blindness.