Galaxy... GXY... Chart..., page-2191

The only value of TA is that of the self-fulfilling prophecy. There is more or less consensus on what certain patterns mean among our chartists and they trade accordingly. There isn't complete consensus and TA is not practiced uniformly.

If TA had any value beyond the (imperfect) self-fulfilling prophecy, then a chartist who operated consistently on the basis of the same assumptions and interpretative rules, would achieve a consistent rate of predictive failure and success. That's how science works. Experiments must be repeatable with identical results otherwise it's ... alternative science.

So a TA practician with a succes rate of up to 50%, while worthless (a complete ignoramus or a goat literally will have the same predictive success rate over time), at least is on to something. The consistent success rate needs to be above 50% to have any value in theory and then it's up to a statitician to work out what success rate above 50% has value in practice. You would, I imagine, need a pretty high rate (75%, 90%?), to make that work as a trading strategy.