Here's some references that you can look up yourself to see the data.
Positive results supportive of mediumship claims
- Dr J. G Pratt (1936) 'Towards a method of evaluating mediumistic material' Bulletin of the Boston Society of Psychical Research, 23
- J. G. Pratt & W. R. Birge (1948) 'Appraisal of verbal test material in parapsychology Journal of parapsychology. 12, 236-256
- Professor Getrude Schmeidler (1958) Analysis and evaluation of proxy session with Mrs Caroline Chapman . Journal of Parapsychology 22 137- 155
- Professor Archie Roy & Patricia Robertson (2001) A preliminary study by the acceptence of non-recipients to medium's statement to recipient Journal of the Society of Psychical Research 65.2, 863, 91-106
- Professor Archie Roy & Patricia Robertson (2004) Results of the application of Roberston-Roy protocol to a series of experiments with mediums and participants ' Journal of the Society for Psychical Research 68.1, 874, 18-34
Professor Archie Roy and Patricia Robertson found positive evidence to support the claim that mediums can communicate with the deceased. Also Professor Gary Schwartz and Dr.Julie Beischel who I made mentioned before also found positive evidence.