And since hydrogen is electrically neutral, it should be possible to observe gravity's tiny tug on it without the confounding effects of electrostatic attraction to other particles.

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Although the findings of the studies are mostly consistent in showing a similar magnitude hazard ratio, estimates of the effectiveness of sipuleucel-T are imprecise due to the relatively small total sample size of the clinical trials, and unmeasurable biases due to potential confounding effects of frozen salvage product and post-progression treatments.

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We have to recognize that studies that carefully assess the effects of an exposure on health are extremely difficult to carry out correctly without the errors of bias and confounding and, thus, are of variable reliability and validity.

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