‘How many participants do I need for my study?’ During many years of providing statistical support to clinical researchers, this has been one of the most frequently asked questions. It is posed by medical students preparing dissertation projects through to seasoned professors preparing major grant proposals. The repetition of this question can be frustrating, but does at least indicate that the...

Given an extensive corpus of reviews on an item, a potential customer goes through the expressed opinions and collects information, in order to form an educated opinion and, ultimately, make a purchase decision. This task is often hindered by false reviews, that fail to capture the true quality of the item’s attributes. These reviews may be based on insufficient information or may even be fraud...

Confident witnesses are deemed more credible than unconfident ones, and accurate witnesses are deemed more credible than inaccurate ones. But are those effects independent? Two experiments show that errors in testimony damage the overall credibility of witnesses who were confident about the erroneous testimony more than that of witnesses who were not confident about it. Furthermore, after makin...

Building on the literature that investigates citizen and voter trust in government, we analyze the topic of voter confidence in the American electoral process. Our data comes from two national telephone surveys where voters were asked the confidence they have that their vote for president in the 2004 election was recorded as intended. We present preliminary evidence that suggests confidence in ...

We report a novel approach to addressing the Raven’s Progressive Matrices (RPM) tests, one based upon purely visual representations. Our technique introduces the calculation of confidence in an answer and the automatic adjustment of level of resolution if that confidence is insufficient. We first describe the nature of the visual analogies found on the RPM. We then exhibit our algorithm and wor...