A downtrend that is so steep and persistent that the stock market shows a net loss for the preceding 12 years creates the sort of oversold conditions that give way to sharp and prolonged periods of strength.
This study focuses on existing structures, which already have known vibrating periods and strength ratios.
It is therefore important that the current samples are followed up regularly and that every effort is made to track individuals during the interim periods – a strength of health and demographic surveillance – in order to ensure a high response rate for these follow-ups.
"All of this is coming after a pretty lengthy period of strength," said Jay Feldman, an economist at Credit Suisse First Boston in New York.
"I feel that every major breakthrough with my running has come after a period of strength training," he said.
Britain's car industry has enjoyed a period of strength over recent years, as cheap finance deals and more efficient models attract consumers.
Hence, in the absence of other news it looks like oil and gold may have made a temporary top, stocks could be due a mini-recovery and the dollar may see an extended period of strength.
Along with celebrity chefs, Russian oligarchs and Italian soccer coaches, hedge funds that established operations here in the last decade have been viewed as a mark of London's new hip spirit of decadent cool — a notion reinforced by the British pound's long period of strength and a housing boom.
The once soaring Turkish stock market has fallen about 9 percent in the past week, interest rates are on the rise and, crucially, after a period of strength, the currency, the lira, has lost 8 percent in recent months and 1 percent just since the protests began.
NPS Pharmaceuticals Short-Term PowerRating 9. 2-period Relative Strength Index (RSI): 11.09.
Pioneer Drilling Short-Term PowerRating 8. 2-period Relative Strength Index (RSI): 5.20.
