Publishing Nutrition Research Validity Reliability and Diagnostic Test

Publishing Nutrition Research: Validity, Reliability, and Diagnostic Test Assessment in Nutrition-Related Research Philip M Gleason, Ph. D: Mathematica Policy Research Jeffrey E Harris, Dr. PH, MPH, RD: West Chester University of Pennsylvania Patricia M Sheean, Ph. D, RD: Northwestern University, Carol J Boushey, Ph. D, MPH, RD: Purdue University Barbara Bruemmer, Ph. D, RD: University of Washington JOURNAL OF THE AMERICAN DIETETIC ASSOCIATION Gleason P, et al. J Am Diet Assoc. 2010; Volume 110 (March).

Publishing Nutrition Research: Validity, Reliability, and Diagnostic Test Assessment in Nutrition-Related Research Study overview Purpose To describe and discuss several concepts related to the measurement of nutrition-related characteristics and outcomes, including validity, reliability, and diagnostic tests. JOURNAL OF THE AMERICAN DIETETIC ASSOCIATION Gleason P, et al. J Am Diet Assoc. 2010; Volume 110 (March).

Publishing Nutrition Research: Validity, Reliability, and Diagnostic Test Assessment in Nutrition-Related Research Baseline data Reliability • Reliability is the extent to which a measurement process gives the same results when repeated under similar circumstances. • Important types of reliability include test-retest, inter-item, and inter-rater or inter-observer reliability. • Analytical tools for assessing reliability include Pearson’s correlation coefficient, Spearman’s nonparametric rank correlation coefficient, a paired ttest, phi coefficient, Cohen’s kappa coefficient, Cronbach’s alpha, KR-20 statistic. From: Gibson RS. Principles of Nutritional Assessment, 2 nd ed. New York, NY: Oxford University Press; 2005. JOURNAL OF THE AMERICAN DIETETIC ASSOCIATION Gleason P, et al. J Am Diet Assoc. 2010; Volume 110 (March).

Publishing Nutrition Research: Validity, Reliability, and Diagnostic Test Assessment in Nutrition-Related Research BMI & Psychosocial measures Validity • Validity is the extent to which a variable or measure captures the concept it is intended to reflect. • Important types of validity: content or face validity, absolute versus relative validity, and internal versus external validity. • Analytical tools for assessing validity include the same set of tools as for assessing reliability. From: Gibson RS. Principles of Nutritional Assessment, 2 nd ed. New York, NY: Oxford University Press; 2005. JOURNAL OF THE AMERICAN DIETETIC ASSOCIATION Gleason P, et al. J Am Diet Assoc. 2010; Volume 110 (March).

Publishing Nutrition Research: Validity, Reliability, and Diagnostic Test Assessment in Nutrition-Related Research Correlation matrix Diagnostic Assessment • Analytical techniques designed to help nutrition professionals and other practitioners diagnose nutrition-related conditions or disorders. Two well known diagnostic tools are sensitivity and specificity. • Sensitivity measures the extent to which a diagnostic test identifies those who have a particular condition or disease; if a person has a condition or disease, a sensitive test will nearly always identify them as having the condition or disease. • Specificity measures the extent to which a diagnostic test identifies those who do not have a particular condition or disease; for those without the condition or disease, a specific test will nearly always be negative. JOURNAL OF THE AMERICAN DIETETIC ASSOCIATION Gleason P, et al. J Am Diet Assoc. 2010; Volume 110 (March).