Sample size bias in the estimation of means

ASU Author/Contributor (non-ASU co-authors, if there are any, appear on document)
Andrew Smith Ph.D, Associate Professor (Creator)
Appalachian State University (ASU )
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Abstract: The present research concerns the hypothesis that intuitive estimates of the arithmetic mean of a sample ofnumbers tend to increase as a function of the sample size; that is, they reflect a systematic sample size bias. A similar bias has been observed when people judge the average member of a group of people on an inferredquantity (e.g., a disease risk; see Price, 2001; Price, Smith, & Lench, 2006). Until now, however, it has been unclear whether it would be observed when the stimuli were numbers, in which case the quantity need not be inferred, and “average” can be precisely defined as the arithmetic mean. In two experiments, participants estimated the arithmetic mean of 12 samples of numbers. In the first experiment, samples of from 5 to 20 numbers were presented simultaneously and participants quickly estimated their mean. In the second experiment, the numbers in each sample were presented sequentially. The results of both experiments confirmed the existenceof a systematic sample size bias.

Additional Information

Smith, A. R. & Price, P. C. (2010). Sample size bias in the estimation of means. Psychonomic Bulletin & Review, 17, 499-503. (ISSN: 1069-9384) version of record avaiable @ (doi:10.3758/PBR.17.4.499)
Language: English
Date: 2010
sample-size, bias, estimation, means

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