The spectral deferred correction (SDC) method is a class of iterative solvers for
ordinary differential equations (ODEs). It can be interpreted as a preconditioned
Picard iteration for the collocation problem. The convergence of this method is well
known, for suitable problems it gains one order per iteration up to the order of the
quadrature method of the collocation problem provided. This appealing feature
enables an easy creation of flexible, high-order accurate methods for ODEs. A
variation of SDC are multilevel spectral deferred corrections (MLSDC). Here,
iterations are performed on a hierarchy of levels and an FAS correction term, as in
nonlinear multigrid methods, couples solutions on different levels. While there
are several numerical examples which show its capabilities and efficiency,
a theoretical convergence proof is still missing. We address this issue. A
proof of the convergence of MLSDC, including the determination of the
convergence rate in the time-step size, will be given and the results of the
theoretical analysis will be numerically demonstrated. It turns out that there are
restrictions for the advantages of this method over SDC regarding the convergence
rate.