They cannot be used to assess the truth value of any claim because the events they describe cannot be independently evaluated or repeated.
The body of research pointed to -- but evidently unread -- by Jabba purports cursory efforts to validate some of the anecdotes that form the basis of their evidence, some 2,500 at the writing of many of the papers. These efforts fall generally into two categories: statistical integrity and external verification.
The statistical methods seem superficially impressive but are entirely unprobative. The quantizations upon which the analyses are based are essentially
ad hoc. They are based on prior art conducted only by Stevenson and lacking any universal validation in the field or use outside his own research. They are applied to samples either blatantly biased or entirely uncontrolled. The conclusions drawn from these analyses purport strength based on such things as consistency over time, or correlations to events whose purported relevance is unclear. The unspoken nulls in these studies would be such notions as detectable changes in the way reincarnation claims are presented. The unspoken assumption is that if the claims had no factual basis, they would change markedly in character from generation to generation.
Similarly for external verification, other studies in this group purport to eliminate potential sources of false credit for the past-life information. However, we find that the purported empirical control is not at all based on external objective fact, but upon testimonial data from sources the researchers simply accept as above reproach. These sources are in almost all cases parents and relatives of the subjects.
Plus they often are filtered through the peoples perceptions based on a desired conclusion by the person reporting it.
The overwhelming majority of subject pools from this body of research come from Eastern countries were reincarnation is a common belief and a desirable aspect of the societal structure. The assumption that testimonial evidence would be unbiased is unsupported. While the authors undertook one study to attempt to correlate the "strength" of the anecdotal evidence to social factors, the study inexplicably considered only internal consistency factors as the dependent variable. What it showed, in effect, was that reincarnation anecdotes coming from a cultural context that favored reincarnation tended to have a high degree of consistency among themselves, as the authors chose to measure consistency. In much of their research they consider consistency synonymous with strength.
As I summed up my comprehensive analysis of Jabba's purported evidence, what we have here is a large body of self-contained, self-referential pseudo-science. While it will fool non-scientists, it is clear there is no actual science being done. It is an exercise evidently designed to convey the semblance of rigor without achieving it. The responses of the researchers to well-founded criticism is especially telling: their answers often boil down to, "Shut up, we know what we're doing."