Angel of Ioren
Friendly Skeptic
Here's a really interesting article about the research being done in Psi and the findings of Dr. Bem that were discussed on this forum recently. I'll post the abstract and a link to the full article:
Eric Jan Wagenmakers, Ruud Wetzels, Denny Borsboom, & Han van
der Maas
University of Amsterdam
Abstract
Does psi exist? In a recent article, Dr. Bem conducted nine studies with
over a thousand participants in an attempt to demonstrate that future events
retroactively affect people’s responses. Here we discuss several limitations
of Bem’s experiments on psi; in particular, we show that the data analysis
was partly exploratory, and that one-sided p-values may overstate the
statistical evidence against the null hypothesis. We reanalyze Bem’s data
using a default Bayesian t-test and show that the evidence for psi is weak
to nonexistent. We argue that in order to convince a skeptical audience of a
controversial claim, one needs to conduct strictly confirmatory studies and
analyze the results with statistical tests that are conservative rather than
liberal. We conclude that Bem’s p-values do not indicate evidence in favor
of precognition; instead, they indicate that experimental psychologists need
to change the way they conduct their experiments and analyze their data.
http://dl.dropbox.com/u/1018886/Bem6.pdf
It's a really interesting article.
Eric Jan Wagenmakers, Ruud Wetzels, Denny Borsboom, & Han van
der Maas
University of Amsterdam
Abstract
Does psi exist? In a recent article, Dr. Bem conducted nine studies with
over a thousand participants in an attempt to demonstrate that future events
retroactively affect people’s responses. Here we discuss several limitations
of Bem’s experiments on psi; in particular, we show that the data analysis
was partly exploratory, and that one-sided p-values may overstate the
statistical evidence against the null hypothesis. We reanalyze Bem’s data
using a default Bayesian t-test and show that the evidence for psi is weak
to nonexistent. We argue that in order to convince a skeptical audience of a
controversial claim, one needs to conduct strictly confirmatory studies and
analyze the results with statistical tests that are conservative rather than
liberal. We conclude that Bem’s p-values do not indicate evidence in favor
of precognition; instead, they indicate that experimental psychologists need
to change the way they conduct their experiments and analyze their data.
http://dl.dropbox.com/u/1018886/Bem6.pdf
It's a really interesting article.