Relative strength of two securities

[Sanford Morton <smorton@xxxxxxxxx>]

I'd like to examine the relative strength or weakness of two securities on
intraday charts. (That is, I am not interested in the Relative Strength
Index.) I'd like to know, for example, of two securities, which often move
together, whether one is a bit stronger on the day than the other.

In looking around for indicators, all I have found are spreads, either
differences or ratios, of the two securities. When compared on
automatically scaled charts, both differences and ratios have remarkably
similar behavior, specifically in the locations and magnitudes of local
extrema.  (Perhaps this is not surprising since one is just a log
transformation of the other). But neither seems to capture what I'm
looking for. Looking at these spreads seems to offer no more insight into
the relative strength of the securities than simply eyeballing and
comparing the individual charts.

Are there other well-know indicators of comparative strength that I have
missed? I haven't come across anything else yet.

Thanks,
Sandy Morton