Objectives: To assess the evidence of published experiments on homeopathic preparations (potencies) that target physical properties (i.e., assumed structural changes in solvents).
Method: A suitable instrument (the Score for Assessment of Physical Experiments on Homeopathy [SAPEH]) was developed through consensus procedure: a scale with 8 items covering 10 criteria, based on the 3 constructs, methodology, presentation, and experiment standardization. REVIEWED PUBLICATIONS: Written reports providing at least minimal details on physical experiments with methods to identify structural changes in solvents were collected. These reports were scored when they concerned agitated preparations in a dilution less than 10(-23), with no other restrictions. We found 44 publications that included 36 experiments (the identity of 2 was unclear). They were classified into 6 types (dielectric strength, 6; galvanic effects, 5; light absorption, 4; nuclear magnetic resonance [NMR], 18; Raman spectroscopy, 7; black boxes of undisclosed design, 4).
Results: Most publications were of low quality (SAPEH < 6), only 6 were of high quality (SAPEH > 7, including 2 points for adequate controls). These report 3 experiments (1 NMR, 2 black boxes), of which 2 claim specific features for homeopathic remedies, as does the only medium-quality experiment with sufficient controls.
Conclusions: Most physical experiments of homeopathic preparations were performed with inadequate controls or had other serious flaws that prevented any meaningful conclusion. Except for those of high quality, all experiments should be repeated using stricter methodology and standardization before they are accepted as indications of special features of homeopathic potencies.