Correspondence

Journal of Parapsychology, The, Fall, 2003 by Stefan Schmidt, James Carpenter, J.E. Kennedy, Susanne Muller, Harald Walach, Rupert Sheldrake, Douglas M. Stokes

To the Editor:

Reading the guest editorial by Dr. James Carpenter QP, 66, 339-342), I was quite puzzled. Dr. Carpenter describes, amongst other examples, the events of September 11, its consequences, and the experience of the situation using "we" as a pronoun. He also made use of verbalizations such as: "Thousands of our countrymen and women...." and "We round a new class of heroes ..."

I do not hold American citizenship, I am not living in the United States, and I think the same applies for quite a lot of the readers of the Journal, which I conceived to be an international journal. This guest editorial is either not addressing the subscribers from abroad or is just ignoring the fact that there are other possibilities than being American.

The perception of the events of 9/11 differs a lot with your nationality, origin, and also with the media bringing you the news. I would like to ask Dr. Carpenter to reread his editorial while simultaneously imaging that he is living somewhere in Europe, South America, or at some other place in the world. I am wondering whether he, as a reader of the Journal, would feel addressed.

STEFAN SCHMIDT

Hornberg Str. 8

79285 Ebringen

Germany

sschmidt@ukl.uni-freiburg.de

To the Editor:

Dr. Schmidt reminds us that the concerns of parapsychology--indeed, all of our deeper concerns--are bigger than any nation. Thanks to him for that. After 9/11 I felt a new love for my country. I loved its shocked innocence; its shaken arrogance. That feeling spilled over into the language of my editorial.

JAMES CARPENTER

Rhine Research Center

2741 Campus Walk Ave., Bldg. 500

Durham, NC, 27705, USA

jcarp@med.unc.edu

To the Editor:

Rex Stanford (2003) recently noted "the wisdom of performing a power analysis prior to attempting replications of a study" (p. 18). Statisticians strongly concur with this point (e.g., Utts, 1991). However, power analysis also brings into focus some of the pivotal and problematic issues in psi research.

Power analysis is used to determine the sample size needed to have a reasonable likelihood of obtaining significant results. It is particularly important for interpreting nonsignificant or marginal results. My experience working in medical research for over a decade has been that power analysis is usually expected as part of grant applications and is required in the protocols for studies submitted to FDA to support approval of new products.

Power analysis, as commonly applied in planning studies, is based on the assumption that the effects being investigated are reasonably stable across studies and reasonably independent of the investigator. The likelihood of obtaining significant results is assumed to increase as the sample size increases.

There is currently strong evidence that psi research does not have these properties. The effects in experiments vary markedly among experimenters. Therefore, any power analysis must be experimenter specific. Even more problematic, the evidence for frequent declines and changes in results for a line of research for an experimenter indicates that psi effects are not stable across studies and often seem to change capriciously (Houtkooper, 2002; Kennedy, 2003).

From a more technical perspective, power analyses, like other statistical methods, are based on the fact that the z score is expected to increase with the square root of the sample size. Similarly, the z score divided by the square root of sample size is used to measure effect size and is expected to be unrelated to sample size.

The expected association between sample size and z score or significance level was not found in meta-analyses of random number generator (RNG) studies (Radin & Nelson, 2000) and early ganzfeld studies (Honorton, 1983). In equivalent results, effect size was found to be inversely related to sample size in RNG studies (Steinkamp, Boller, & Bosch, 2002), later ganzfeld studies (Bem & Honorton, 1994) and early card experiments (Nash, 1989; discussed in Kennedy, 1994). These findings are another way of expressing the experimenter differences and declines noted above, and are also consistent with goal-oriented psi experimenter effects (Kennedy, 1994).

Much greater thought needs to be given to the application and interpretation of statistical methods under these circumstances. Trying to use power analysis to plan the sample size for confirmatory studies brings these issues to the forefront.

It appears to me that understanding these problematic properties of psi is the top priority for research. Historically in parapsychology the inconsistent effects have been thought to be due to variations in psychological factors such as attitude and motivation. That is certainly one of the more testable approaches and is a good starting point. However, there has been little effort to explore these realms in depth--to understand what peoples' actual motivations are relating to psi and why they feel and believe that way.

For example, it appears that the sex differences in attitude toward psi and the occurrence of psi experiences is an area of interest whose time has come. In the last issue of the Journal, I discussed evidence that the extreme skeptics tend to be males who have rational, controlling personalities, and the likelihood that these personality factors are genetically based and have had adaptive value in evolution (Kennedy, 2003). In the same issue, Stanford (2003) commented that gender is likely to be a significant factor in psi research and should always be examined. Palmer and Neppe (2003) reported a study that found the overall association between psi experiences and temporal lobe dysfunction was confounded by greater reports of experiences and symptoms by females. It also can be noted that Watt and Ramakers (2003) reported a study that recruited favorable and skeptical experimenters, which resulted in 6 of the 9 believers being female and 3 of the 5 skeptics being male.