  In the tests for macrorealism proposed by Leggett and Garg, the temporal
correlation functions of a dichotomic variable Q must be measured in a
non-invasive way to rule out alternative classical explanations of Leggett-Garg
inequality violations. Ideal negative measurements, in which a null result is
argued to be a non-invasive determination of the system's state, are often
used. From a quantum-mechanical perspective, such a measurement collapses the
wave function and will therefore typically be found to be invasive under any
experimental check. Here, a simple modified ideal negative measurement protocol
is described for measuring the correlation functions which is argued to be
non-invasive from both classical and quantum perspectives and hence the
non-invasiveness can then be checked experimentally, thereby permitting a
quantitative measure of the degree of clumsiness of the measurement. It is also
shown how this procedure may be extended to measure higher-order correlation
functions and a number of higher-order conditions for macrorealism are derived.
