  We derive a hierarchy of equations which allow a general $n$-body
distribution function to be measured by test-particle insertion of between $1$
and $n$ particles, and successfully apply it to measure the pair and three-body
distribution functions in a simple fluid. The insertion-based methods overcome
the drawbacks of the conventional distance-histogram approach, offering
enhanced structural resolution and a more straightforward normalisation. They
will be especially useful in characterising the structure of inhomogeneous
fluids and investigating closure approximations in liquid state theory.
