Statistical judgments are influenced by the implied likelihood that samples represent the same population
 Dana L. Chesney,
 Natalie A. Obrecht
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Abstract
When sample information is combined, it is generally considered normative to weight information based on larger samples more heavily than information based on smaller samples. However, if samples appear likely to have been drawn from different subpopulations, it is reasonable to combine estimates of these subpopulation means (typically, the sample means) without weighting these estimates by sample size. This study investigated whether laypeople are influenced by the likelihood of samples coming from the same population when determining how to combine information. In two experiments we show that (1) implied binomial variability affected participants’ judgments of the likelihood that a sample was drawn from a given population, (2) participants' judgments were more affected by sample size when samples were implied to be drawn randomly from a general population, compared to when they were implied to be drawn from different subpopulations, and (3) people higher in numeracy gave more normative responses. We conclude that when determining how to weight and combine samples, laypeople use not only the provided data, but also information about likelihood and sampling processes that these data imply.
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 Title
 Statistical judgments are influenced by the implied likelihood that samples represent the same population
 Journal

Memory & Cognition
Volume 40, Issue 3 , pp 420433
 Cover Date
 20120401
 DOI
 10.3758/s1342101101553
 Print ISSN
 0090502X
 Online ISSN
 15325946
 Publisher
 SpringerVerlag
 Additional Links
 Topics
 Keywords

 Judgment
 Reasoning
 Inductive reasoning
 Mathematical cognition
 Individual differences
 Industry Sectors
 Authors

 Dana L. Chesney ^{(1)}
 Natalie A. Obrecht ^{(2)}
 Author Affiliations

 1. Department of Psychology, University of Notre Dame, 118 Haggar Hall, Notre Dame, IN, 46556, USA
 2. Department of Psychology, William Paterson University, 300 Pompton Road, Wayne, NJ, 07470, USA