Sometimes, an important indication of market strength is the absence of weakness.

An interesting example comes from the Stockspotter site, which offers cycle-based forecasts for stocks and ETFs. I've tracked the cumulative number of buy and sell signals from the site since late 2013. When there have been fewer than 10 sell signals on a given day (N = 225), the next ten days in SPY have averaged a gain of +.47%. When there have been more than 10 sell signals on a given day (N = 317), the next ten days have averaged a loss of -.06%. Interestingly, when there were few sell signals, the number of buy signals didn't matter. It was the absence of weakness that was most important.