What is Isolation method, apparent order?

In the isolation method, all reactants but one are put in large excess (ten times or more). Their concentrations stay practically constant, and $v = k[\ce{A}]^p[\ce{B}]^q \approx k'[\ce{A}]^p$ with $k' = k[\ce{B}]_0^q$: the reaction behaves as if of apparent order $p$ with the apparent rate constant $k'$. This is also called degeneracy of the order.