As price increases or decreases in value, the swing trader should see momentum confirmation with a new high or new low.
As price increases or decreases, the swing trader wants to see this change mirrored by momentum. In this way, momentum is a confirmation of what you're seeing in price in the price chart. Rising or falling momentum can be a box that's ticked prior to the decision to trade. If your trading system signals a buy or sell, momentum can confirm that signal.
The basic principle of the first backtest was the premise that buying an ETF of a country's equity index that had previously performed well would produce profits. A portfolio was created of a variety of ETFs from those in Europe, Asia, South America, North America. This was a long-only strategy.