@Db,
I read a couple of places that referred to springs and shake outs as a test of supply. E.g.,
"A spring is a price move below the support level of a trading range that quickly reverses and moves back into the range." link
A spring is a price move below the support level of a trading range that quickly reverses and moves back into the range
@MightMouse,
I am not sure what you mean by "ex post facto", but a successful spring with low volume would indicate that supply "is or might be" available below support.
The article to which you refer is based not on Wyckoff but on Robert Evans' interpretation of Wyckoff. There are no "springs" nor creeks nor ice. There is no "law of cause and effect" nor is there a "law of effort vs result". This is not to say that the Evans version is not useable. But it isn't Wyckoff. If you want to learn Wyckoff's approach, study Wyckoff's course. You will likely find that doing so at this point will be exceptionally difficult due to your having so much to unlearn.
FWIW, I decided a couple of years ago to stop arguing about this and pursue another path: the SLA. In fact, I posted the following to another site just yesterday:
The SLA/AMT is a reset. After years of arguing about what's Wyckoff and what's VSA and what's Evans and what's SMI and trying to sort it all out, I finally two years ago started from scratch. If traders want to break through ice and jump creeks, they are welcome to do so, but that no longer has anything to do with me. Rather than spend/waste seemingly endless amounts of time arguing about what is or is not Wyckoff, I can ask that those who are interested in all this focus on the SLA and implementing the SLA. As the SLA is about as simple as it gets with regard to trading price and as the entire thing is one-fifth the length of Wyckoff's course (100p vs 500p) and the condensed version posted to the first post is one-fifth of that (20p), and as one can approach it without testing and with minimal journaling, the primary task for the intended becomes extinguishing bad habits and learning new ones, rather than slogging through hundreds of pages and thousands of posts. The SLA is based on and stems from Wyckoff, but one can study it and practice it and trade it without ever having heard of Wyckoff or having read a single word of his course.
You are of course welcome to study Wyckoff in the original and ask whatever questions occur to you. But if you choose not to do so, you won't be alone. The SLA is far simpler and far easier to understand.
You may also be interested in this post.