= Positive and negative likelihood ratios = Slide ten of these [[attachment:posneglik.pdf | pdf slides]] indicates rules of thumb for assessing positive and negative likelihood ratios to evaluate them to assess discrimination of the model. where Positive likelihood ratio = Sensitivity / (1 - Specificity) Negative likelihood ratio = (1 - Sensitivity) / Specificity The slides also briefly mention Hierarchical ROC curves which are useful for plotting curves combining within and between study variances from studies in meta-analyses. __Reference__ Jaeschke R, Guyatt, GH and Saclett DL (1994) Users guides to the medical literature. III. How to use an article abotu a diagnostic test. B. What are the results and will they help me in caring for my patients? The Evidence-Based medicine Working Group. ''Journal of the American medical Association'', '''271(9)''', 703-707.