http://econviz.org/macroeconomic-balance-sheet-visualizer/

Visual how money works in the economy.  Shows the balance sheets of the Fed, Treasury, Households, Banks, and Companies.  It shows how the treasury spends, Fed controls monetary policy, treasury taxes, household / banks get loans, companies get loans.

Prospect Theory - based on the way a problem is framed ( make X amount vs I will loose X amount), different outcomes are chosen.

Since people are loss averse, a loss the same size as a gain has a much greater affect (Prospect Theory).  Also the prospect of a small loss vs a large gain is undesirable (myopic loss aversion).  So if presented an opportunity that was favorable, it would not be taken because of this (Equity premium puzzle - stocks have outperformed bonds but standard economic theory says that .  However framing the question differently may lead to taking that risk (ie: thinking in another language led to better results because less emotional bias was used in deliberation)

how much equity to invest during a decline, if you want to be fully invested after a 50% sell off

decline	equity to invest	start equity	equity after decline	% of original equity invested
2.5	2	100.0	98.0	2%
7.5	10	97.9	88.1	10%
12.5	17	87.6	72.7	15%
20	28	71.4	51.4	20%
35	42	47.2	27.4	20%
50	100	21.1	0	21%

Since 1928 there have been 294 pullbacks of at least 5%.  

94  (>10%)

43  (>15%) 

25 (>20%) bear market

So in a statistical sense once you hit the 5% threshold your chances of a 10%, 15%, and 20%+ drop are as follows:

10%: 32.0%

15%:  14.6%

20%+: 8.5%