DAG_Stat provides a comprehensive range of statistics calculable from 2 by 2 tables that are useful in evaluating diagnostic tests and interrater agreement. Statistics for the evaluation of diagnostic tests include sensitivity, sensitivity of a random test given the observed prevalence and test level., sensitivity quality index, specificity, specificity of a random test, specificity quality index, efficiency (the correct classification rate), efficiency of a random test, quality index, Youden's index, the predictive value of positive test, predictive value of a positive random test, predictive value of negative test, predictive. value of a negative random test, likelihood ratio of a positive and negative tests, the odds ratio. Also included are the false positive and false negative rates, prevalence observed in the sample and test level (proportion of subjects classified as 'positive.' For investigating interrater agreement DAG_Stat calculates Cohen's Kappa, observed agreement, chance agreement, agreement about positive and negative cases, Byrt's bias index, Byrt's prevalence asymmetry index, bias adjusted Kappa, prevalence & bias adjusted Kappa. DAG_Stat also calculates Dice's index, Yule's Q (Gamma), Phi, Scott's agreement index, the tetrachoric correlation coefficient, Goodman & Kruskal's tau, Lambda, the Uncertainty Coefficient, Pearson's Chi Square (with and without Yates' correction), the likelihood ratio Chi Square, McNemar's Test, (with and without Yate's correction).
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Links and References
Download DAG_Stat in Microsoft Excel 2003 compatible format. (Also suitable for more recent versions of Excel.)
Notes on Downloading and Opening DAG_Stat Because browsers have varied and unpredictable responses when downloading Excel spreadsheets, DAG_Stat is also available as a Zip file. Depending on your browser's configuration, the download may be automatically unarchived and saved as an Excel file, or you may have to UnZip the file manually. You may need to right-click(Windows) or control-click(Mac) the link to download the file.
When you open DAG_Stat, Excel may display a message telling you that the file contains macros. Because it is possible to write macros that modify or damage files, Excel gives you the option of not opening the file or disabling macros. DAG_Stat will run perfectly well without the macros: they add only minor functions to the spreadsheet.
If you use results calculated using DAG_Stat in reports or publications, I would be grateful if you cited the paper describing DAG_Stat. (Reprints are available on request below. Citing the paper enables readers of your work to resolve any queries they about the statistics used (for instance, with the asymetry of the exact confidence intervals compared to the more commonly used normal approximation). Citations also provide evidence to our various funding bodies that our work makes a contribution to research. Thanks in advance!
Up to 2010, nearly seventy papers in a broad range of areas have used DAG_Stat to calculate diagnostic or agreement statistics. Click here for a list of papers published to date.
It is a pdf of approximately 100K.
DAG_Stat is an acronym for Diagnostic and AGreement Statistics. However, the word 'dag' has a unique place in Australian culture. Perhaps it's best to consult the dictionary...
dag /dag/ n. LME. [Origin unkn.: cf. TAG n.] 3. In full dag-lock. A lock of wool clotted with dung about the hind legs of a sheep. Usu. in pl. Now chiefly in Austral. & NZ. E17. 4 An extraordinary person; a character; a tough but amusing person. Austral. & NZ slang. E20.
(The New Shorter Oxford English Dictionary)