On ROC analysis with nonbinary reference standard.

Statistical methods for the evaluation of the accuracy of diagnostic tests usually assume a binary true disease status. However, this assumption may not be realistic in practical settings in which "disease" is defined by dichotomizing continuous or ordinal categorical measures using a pre-specified threshold value. In this paper, we focus on the analysis of studies in which both the diagnostic test and the reference standard are reported as continuous measures.

Anti-diabetic properties of three common Bidens pilosa variants in Taiwan.

Bidens pilosa L. var. radiata (BPR), B.

How do Mothers, Fathers, and Friends Influence Stages of Adolescent Smoking?

Parent and friend influences may differentially promote or deter adolescent smoking at discrete stages. Drawing from national (Add Health) data, a partial proportional odds ordinal regression model was utilized to examine the multivariate influence of parent and friend variables and their interactions on transitions across smoking stages (Never Smokers, Experimenters, Intermittent, Regular/Established) separately for mother-child pairs (N = 15,983) and father-child pairs (N = 1,142). Friend smoking status was by far the strongest predictor across smoking stages.

The predictive receiver operating characteristic curve for the joint assessment of the positive and negative predictive values.

Binary test outcomes typically result from dichotomizing a continuous test variable, observable or latent. The effect of the threshold for test positivity on test sensitivity and specificity has been studied extensively in receiver operating characteristic (ROC) analysis. However, considerably less attention has been given to the study of the effect of the positivity threshold on the predictive value of a test.

Exercise participation after diagnosis of breast cancer: trends and effects on mood and quality of life.

Individuals treated for cancer often experience higher levels of emotional distress than the general population. Previous research has shown that exercise can have an ameliorating effect on these problems. This 12-month prospective longitudinal study investigated mood, quality of life, cancer-related symptoms, and exercise behavior of 69 women who had completed treatment for Stage 0-2 breast cancer.