In an investigation involving parapsychology, it can be useful to do a field experiment (or multiple) to get an idea of what exactly happened. In some cases, the phenomenon may repeat itself if the conditions are very similar.
In a haunting or apparition case, try to see if all witnesses get the same perceptions of the ''presence'' by having them not only describe what is seen and heard, but also run down a checklist of descriptive adjectives which help form a ''picture'' of the ''personality'' that the presence may be. To help pin down what is happening in a haunting or apparition case, have everyone involved (and a group of mediums, if necessary) each give independent assessments of what they think is going on. One can take all independent lists and see if the perceptions of what is going on are similar or not.
Instructions: Circle those descriptive terms that seem to relate to the ghost's activity or intent. Cross out any terms that are opposite to what you think relates to the ghost or presence. Those terms that are not applicable you can just leave alone.
List first published in the 'Journal of the American Society for Psychical Research' (volume 62, October 1968) in the article "Quantitative Investigation of a 'Haunted House' with Sensitives and a Control Group".