The phrase level of effort in the sphere of project management can and typically does have reference to any particular support type activity that customarily does not lend itself to the ultimate establishment via measure of the sum total of discrete accomplishment. The phrase level of effort, when the desire to be brief exists, can be referred to through the use of the three letter anagram LOE. Some examples of support type activities that can lend itself to the properties described previously here are those such as a customer liaison, a seller liaison, project management activities of assorted types, as well as some means of project cost accounting. The level of effort is typically denoted through and via a uniform set of work performance rates over a period of time (typically a pre-defined period of time) over which the activities of note took place. Level of effort can be measured via an independent observation or by members of the project group.
This term is defined in the 3rd edition of the PMBOK but not in the 4th.