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Med Decis Making. 2016 Aug;36(6):686-91. doi: 10.1177/0272989X16640785. Epub 2016 Mar 31.

Natural Frequencies Do Not Foster Public Understanding of Medical Test Results.

Author information

1
Center for Experimental Research in Management and Economics, DCP, University IUAV of Venice, Venice, Italy (SP, VG)
2
Laboratory of Cognitive Psychology, CNRS and Aix-Marseille University, Marseille, France (MG)
3
Department of Economics and Management, University of Trento, Trento, Italy (LS)

Abstract

Major organizations recommend presenting medical test results in terms of natural frequencies, rather than single-event probabilities. The evidence, however, is that natural frequency presentations benefit at most one-fifth of samples of health service users and patients. Only one study reported a substantial benefit of these presentations. Here, we replicate that study, testing online survey respondents. Study 1 attributed the previously reported benefit of natural frequencies to a scoring artifact. Study 2 showed that natural frequencies may elicit evaluations that conflict with the normatively correct one, potentially hindering informed decision making. Ironically, these evaluations occurred less often when respondents reasoned about single-event probabilities. These results suggest caution in promoting natural frequencies as the best way to communicate medical test data to health service users and patients.

KEYWORDS:

diagnostic reasoning, numeracy; natural frequencies; single-event probability; test result understanding

PMID:
27034447
DOI:
10.1177/0272989X16640785
[Indexed for MEDLINE]

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