Here are some examples of subjective probabilities fromDoug Kass’s daily diary, August 29, 2011:

I am building my baseline 12-month S&P 500 price forecast based on four different economic scenarios, applying a probability to each outcome and then assuming an expected market reaction under each case. (You, home-gamers, too, can use this outline and input your own assumptions and probabilities to personalize your forecasts.)

Scenario No. 1 (probability 15%): The pace of U.S. economic recovery reaccelerates to above-consensus forecasts based on pro-growth fiscal policies geared toward generating job growth), still low inflation, subdued interest rates and the adoption of aggressive plans by the government to deplete the excess inventory of unsold homes. Corporate profits meet consensus for 2011, and 2012 earnings estimates are raised (modestly). Europe stabilizes, and China has a soft landing. Stocks have 25% to 30% upside over the next 12 months. S&P target is 1500.

Scenario No. 2 (probability 15%): The U.S. enters a deep recession precipitated by a more pronounced negative feedback loop, a series of European bank failures and likely sovereign debt defaults in the eurozone. While 2011 corporate profits and margins disappoint somewhat (we are already well into full-year results), 2012 earnings estimates are materially slashed. China has a hard landing. Stocks have a 20% to 30% downside risk over the next 12 months. S&P target is 885.

Scenario No. 3 (probability 30%): The U.S. and Europe economies experience a shallow recession. Earnings for 2011 are slightly below expectations, but 2012 corporate profits are cut back to slightly below this year's levels. Stocks have 10% to 15% downside risk over the next 12 months. S&P target is 1030.

Scenario No. 4 (probability 40%): The U.S. and European economies “muddle through” in a modest expansion mode (hat tip for the term to John Mauldin). Profits for 2011 meet consensus expectations, but slippage in margins brings down 2012 corporate profit growth projections somewhat. Stocks have 10% to 20% upside over the next 12 months. S&P target is 1355.