Single-Item Measurement of Suicidal Behaviors: Validity and Consequences of Misclassification

PLoS One. 2015 Oct 23;10(10):e0141606. doi: 10.1371/journal.pone.0141606. eCollection 2015.


Suicide is a leading cause of death worldwide. Although research has made strides in better defining suicidal behaviors, there has been less focus on accurate measurement. Currently, the widespread use of self-report, single-item questions to assess suicide ideation, plans and attempts may contribute to measurement problems and misclassification. We examined the validity of single-item measurement and the potential for statistical errors. Over 1,500 participants completed an online survey containing single-item questions regarding a history of suicidal behaviors, followed by questions with more precise language, multiple response options and narrative responses to examine the validity of single-item questions. We also conducted simulations to test whether common statistical tests are robust against the degree of misclassification produced by the use of single-items. We found that 11.3% of participants that endorsed a single-item suicide attempt measure engaged in behavior that would not meet the standard definition of a suicide attempt. Similarly, 8.8% of those who endorsed a single-item measure of suicide ideation endorsed thoughts that would not meet standard definitions of suicide ideation. Statistical simulations revealed that this level of misclassification substantially decreases statistical power and increases the likelihood of false conclusions from statistical tests. Providing a wider range of response options for each item reduced the misclassification rate by approximately half. Overall, the use of single-item, self-report questions to assess the presence of suicidal behaviors leads to misclassification, increasing the likelihood of statistical decision errors. Improving the measurement of suicidal behaviors is critical to increase understanding and prevention of suicide.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • Aged
  • Female
  • Humans
  • Male
  • Middle Aged
  • Suicide / classification*
  • Suicide / statistics & numerical data
  • Suicide Prevention
  • Surveys and Questionnaires
  • United States / epidemiology
  • Young Adult

Grant support

AJM received a Sackler Scholars Program in Psychobiology grant given to students within the Department of Psychology at Harvard University from the Dr Mortimer and Theresa Sackler Foundation. MKN received funding from the John D. and Catherine T. MacArthur Foundation. There is no specific grant number. The Sackler and MacArthur Foundations had no influence or input into any aspect of the study (e.g., planning or execution), writing of the manuscript or submission process.