Really: think about causal factors before 1920 and those since 2000. Really? Just plot a few straight lines on a graph with linear percent vertically and a variable time axis horizontally? Of course, the shorter the interval, the more volatility. The last two intervals are prediction. Piketty makes valuable points in "Capital in the 21st Century", including causes, but his focus is on growing inequality generated by the difference between ROC and earned income. Stocks did very well in 2009 - 20014; median earned income? Not so much.

Piketty postulates and presents some evidence for behavior of this graph; read the book.

Nate Silver, he of notably accurate political predictions, uses Bayesian statistics. Bayesian statistics use an iterative process to increasingly refine and improve predictions based on new data and modeling dominant causes. His successes demonstrate the importance of causality. Some of the comments above discuss causality in generalities. ]]>

Really: think about causal factors before 1920 and those since 2000. Really? Just plot a few straight lines on a graph with linear percent vertically and a variable time axis horizontally? Of course, the shorter the interval, the more volatility. The last two intervals are prediction. Piketty makes valuable points in "Capital in the 21st Century", including causes, but his focus is on growing inequality generated by the difference between ROC and earned income. Stocks did very well in 2009 - 20014; median earned income? Not so much.

Piketty postulates and presents some evidence for behavior of this graph; read the book.

Nate Silver, he of notably accurate political predictions, uses Bayesian statistics. Bayesian statistics use an iterative process to increasingly refine and improve predictions based on new data and modeling dominant causes. His successes demonstrate the importance of causality. Some of the comments above discuss causality in generalities. ]]>

Conclusion: relatively small differences in the combinations of these variables or their timing (inclusive or) make very big differences in the long term outcome. For my case, age 72 and wife's age 63, "long term" is 30 - 40 years. Life isn't this simple, even including some of the modifiers in the previous comments. Keep connected to what's going, on, control what you can, don't overreact, understand your priorities. Good luck.]]>

Conclusion: relatively small differences in the combinations of these variables or their timing (inclusive or) make very big differences in the long term outcome. For my case, age 72 and wife's age 63, "long term" is 30 - 40 years. Life isn't this simple, even including some of the modifiers in the previous comments. Keep connected to what's going, on, control what you can, don't overreact, understand your priorities. Good luck.]]>