Validation of a Short, 3-Item Version of the Subjective Numeracy Scale

Med Decis Making. 2015 Nov;35(8):932-6. doi: 10.1177/0272989X15581800. Epub 2015 Apr 15.


Background and objective: Efficiency in scale design reduces respondent burden. A brief but reliable measure of numeracy may provide a useful research tool eligible for integration into large epidemiological studies or clinical trials. Our goal was to validate a 3-item version of the Subjective Numeracy Scale (SNS-3).

Design and setting: We examined 7 separate cross-sectional data sets: patients in the emergency department (n = 208), clinic (n = 205), and hospital (n = 460; n = 2053) and patients with chronic kidney disease (n = 147), with diabetes (n = 318), and on hemodialysis (n = 143).

Measurements: Internal reliability of the SNS-3 was assessed with Cronbach's α. Criterion validity was determined by nonparametric correlations of the SNS-3 with SNS-8 and other measures of numeracy; construct validity was determined by correlations with measures of health literacy and education.

Results: The SNS-3 had good internal reliability (median Cronbach's α = 0.78) and correlated highly with the full SNS (median ρ = 0.91). The SNS-3 was significantly correlated with other measures of numeracy (e.g., median ρ = 0.57 with the Wide Range Achievement Test 4), health literacy (e.g., median ρ = 0.35 with the Shortened Test of Functional Health Literacy in Adults), and education (median ρ = 0.41), providing good evidence of criterion and construct validity.

Conclusion: The SNS-3 is sufficiently reliable and valid to be used as a measure of subjective numeracy.

Keywords: health literacy; numeracy; psychometric models; scale development.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, U.S. Gov't, Non-P.H.S.
  • Validation Study

MeSH terms

  • Academic Medical Centers
  • Acute Coronary Syndrome
  • Cross-Sectional Studies
  • Diabetes Mellitus
  • Educational Measurement / methods*
  • Educational Measurement / standards*
  • Emergency Service, Hospital
  • Health Literacy / methods*
  • Health Literacy / standards*
  • Hospitals
  • Humans
  • Hypertension
  • Mathematics*
  • Psychometrics
  • Renal Dialysis
  • Renal Insufficiency, Chronic
  • Reproducibility of Results