Wyckoff analysis to calculate TP/target out of a range involves using a 'point and figure' chart. Reliability of these calculations are based on past accuracy when used in the current market - backtesting, if you will.
The market currently appears to be in a markdown as has been illustrated with the that price currently sits in. In order to test where price may end up as a target, we can find a previous consolidation range and see how accurate it's point and figure chart settings/sizings are.
The accumulation range marked up on the left has a TP range at the top of the chart in blue. As you can see, this was incredibly accurate. The same settings (close, 0.0005 box size, 3 box reversal) were used to calculate a target for the current distribution markdown. This has been drawn with another blue box on the right hand side.
Time will tell how accurate I am again. Minor inaccuracies in this method of TP calculation will occur between/for all Wyckoffians due to factors including but not limited to: counting columns in 'point and figure' counts, differences in range behaviour and differences in number of supply/demand lines in ranges, fundamental shifts etc. Wyckoff's TP projections are to be seen more as a 'guideline' than a hard and fast rule.
Any questions are welcome.