The correction already reached its first objective which is $15,700 which is just a Fibonacci level same as the recent top. Any fright between those two prices is just the audience
How do you calculate the fib levels? OK, so the top is ~20k. How do you figure the bottom, to get the fib retracement to be 15.7?
Im just an amateur but I use the site bitcoinwisdom which has a Fibonacci tool. I look for the most significant area and then plot in extensions as per the graph tools provided. So taking the November selloff you get projections for significant areas such as the recent ATH and the possible pullback area of $15,771 which did appear to me to have some support before becoming a top some hours ago.
We are returning to November prices here, theres never any certain bottom price its just an aid to judging better movement.