Warren Buffett says he buys companies with the anticipation that even if the stock market closes for five years; he won't even blink about his investments. In such a situation, they will have no idea how their investment is doing. But since they've analyzed the company and bought a stake in a fundamental business, they'll be able to keep track of how the real business is doing. If the trade is going well, they won't care what the market says or if it's closed if he says anything. Buffett repeatedly emphasizes that you "buy bearish, sell bullish" rather than "buy bullish, sell bearish," as many investors eventually do.
Buffett has outlined a simple and basic requirement for individual trading and stock analysis. Since predictions can be wrong and market volatility is bound to happen, any investment should have a good margin of safety to offset the uncertainty.
A useful book analyzing Warren Buffett's stock buying techniques.