From wikipedia: """In 1885, Hermann Ebbinghaus discovered the exponential nature of forgetting. The following formula can roughly describe it: $R = e^{-t/s}$ where $R$ is memory retention, $S$ is the relative strength of memory, and $t$ is time.""" http://en.wikipedia.org/wiki/Forgetting_curve
I'd just like to understand what this math is trying to say. Such that if I want $100\%$ retention level of something, thus as my relative strength is less the more time it will take to remember something. But also that as my retention increases, the less amount of time it takes to have strength of memory reviewed.
So I suppose I can articulate it, but how can I use the equation to roughly calculate how I'm doing remembering something?
Wolfram Alpha puts $t = -s \log(R)$ and gives a funky 3D graph. But if I use $R=1$ then $t=0$. If $R=100$, $t=-900$. So a bit confusing. I think the wikipedia graphic is more germane to understanding that as the y axis is R and that the graph exponentially decays, but at a different rate for each new iteration. Kicking the can down the road so to speak...
So let's go for a low, medium and high retention graph based on hours in a day. How can this be used in the formula to determine the time needed to study something again?
Let's say I have a class at 8am and I want to review it. I'll have to review it early on, then increasingly less. I'm just trying to ballpark when the best time to study is based on this decay graph.
Hope that makes sense.