False positives and other statistical errors in standard analyses of eye movements in reading.

von der Malsburg, T. and Angele, B., 2017. False positives and other statistical errors in standard analyses of eye movements in reading. Journal of Memory and Language, 94 (June), 119 - 133.

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DOI: 10.1016/j.jml.2016.10.003

Abstract

In research on eye movements in reading, it is common to analyze a number of canonical dependent measures to study how the effects of a manipulation unfold over time. Although this gives rise to the well-known multiple comparisons problem, i.e. an inflated probability that the null hypothesis is incorrectly rejected (Type I error), it is accepted standard practice not to apply any correction procedures. Instead, there appears to be a widespread belief that corrections are not necessary because the increase in false positives is too small to matter. To our knowledge, no formal argument has ever been presented to justify this assumption. Here, we report a computational investigation of this issue using Monte Carlo simulations. Our results show that, contrary to conventional wisdom, false positives are increased to unacceptable levels when no corrections are applied. Our simulations also show that counter-measures like the Bonferroni correction keep false positives in check while reducing statistical power only moderately. Hence, there is little reason why such corrections should not be made a standard requirement. Further, we discuss three statistical illusions that can arise when statistical power is low, and we show how power can be improved to prevent these illusions. In sum, our work renders a detailed picture of the various types of statistical errors than can occur in studies of reading behavior and we provide concrete guidance about how these errors can be avoided.

Item Type:Article
ISSN:0749-596X
Uncontrolled Keywords:Statistics; False positives; Null-hypothesis testing; Eye-tracking; Reading; Sentence processing
Group:Faculty of Science & Technology
ID Code:27412
Deposited By: Unnamed user with email symplectic@symplectic
Deposited On:13 Mar 2017 10:02
Last Modified:13 Mar 2017 10:02

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