Couch Potato investors, like most investors, have no reason to celebrate 2015. The most basic Couch Potato portfolio is a 50/50 mix of a total domestic market index fund and an inflation-protected Treasury securities index fund. It’s a simple mix: if you can fog a mirror and divide by the number “2” you can do this. And, yes, you can use a hand-held calculator!

The Couch Potato portfolio lost about 0.74 percent for the year. Sounds pretty dismal, right?

Wrong. It was worse for most investors. According to Morningstar, the Chicago firm that tracks all things fund-related, the average return of all funds it calls “moderate allocation” was a loss of 1.93 percent. In other words, the slothful approach I’ve been advocating for many years has, yet again, shown a material advantage over the ever-so-hard work of the geniuses constantly thinking-of-your welfare on Wall Street.

Kind of makes you wonder.

You might also note that the Couch Potato advantage is pretty big. The lazy Couch Potato investor lost 1.19 percent less for the year than all those people competing to be the proverbial smartest guys in the room.

But let’s not dwell on the negative. Is there any way to do better than the Couch Potato portfolio, with little or no effort?

Indeed, there was. Vanguard Balanced Index Fund Investor Shares (ticker VBINX), frequently mentioned in this column, provided a positive return of 0.37 percent for the year. The return left 86 percent of managed funds in the same category in the dust, looking for excuses.

Think about it. This fund, a traditional 60/40 mix of domestic stocks and bonds that operates with an annual expense ratio of 0.23 percent, did better than the vast majority of managed funds. It beat the average fund by a stunning 2.29 percent for the year. The Admiral Shares version of the same fund, with an expense ratio of 0.09 percent and a minimum investment of $10,000, returned 0.51 percent. It beat the average fund by 2.44 percent for the year.

Was it a fluke? Is the return advantage always a roaring 2.29 or 2.44 percent?

Nope. But it has been happening with enough regularity that the investor shares of the fund have done better than 76 percent of its surviving competition over the last 15 years, providing an annualized return of 5.58 percent. That’s 0.77 percent a year higher than the category average.

These return advantages confirm the original Couch Potato thesis: dirt-simple, low-cost index investing is a better way for most of us to invest than anything— repeat, anything— Wall Street wants to sell us.

That leaves us with two questions. First, what caused the Couch Potato portfolio to trail the even simpler single fund choice by so much, even if it beat the managed funds? Second, is there a way to build a clone of the Vanguard Balanced Index Fund without having an account at Vanguard?

The answer to the first question is simple. The basic Couch Potato portfolio uses an inflation protected Treasury index for bonds. While it beat the more conventional total bond index for many years, it has done relatively poorly in recent years. In 2015, for instance, the iShares ETF version of this index lost 1.75 percent. The Vanguard Inflation Protected Securities Fund lost 1.83 percent. Both trailed the 0.56 percent return of the Vanguard Total Bond Market Index ETF. The return gap was even larger over the last three years.

Does that mean inflation-protected Treasury bonds are a bad investment? Maybe, maybe not. The advantage could reverse if we go from a period of disappearing inflation to a period of rising inflation.

If you are willing to use that hand-held calculator that Couch Potato investors use, you can multiply your investment by 0.6 and 0.4 to get the amount that should be invested in each fund. This will create your own version of the Vanguard Balanced Index Fund on virtually any brokerage platform— often without commissions and at somewhat lower cost than Vanguard. Admiral Shares of Vanguard Balanced Index Fund (ticker VBIAX) require a minimum investment of $10,000 but have an expense ratio of 0.09 percent.

You can come very close to duplicating the fund at Schwab by using the Schwab ETFs, Schwab U.S. Broad Market (ticker SCHB) and Schwab U.S. Aggregate Bond (ticker SCHZ). At Fidelity you’ll come close by using Fidelity Spartan Total Market Index Fund (ticker FSTMX) and Fidelity Spartan U.S. Bond Index Fund (ticker FBIDX). Both funds are available in Investor Class (min. $2,500) or Advantage Class (min. $10,000). The Advantage Class shares have lower expense ratios.