2018 AAPM Annual Meeting
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Session Title: The Anne and Donald Herbert Distinguished Lectureship in Modern Statistical Modeling
Question 1: Which of the following is NOT true about calibration, discrimination and clinical utility?
Reference:Ewout W. Steyerberg, et al. Assessing the performance of prediction models: a framework for some traditional and novel measures, Epidemiology (Cambridge, Mass). 2010;21(1):128-138. doi:10.1097/EDE.0b013e3181c30fb2.
Choice A:A prediction model with a high discrimination will be clinically useful, unless it is miscalibrated.
Choice B:Calibration and discrimination are important to help statisticians build better models, but they don’t tell us much about whether a prediction model is of value.
Choice C:Calibration is what is most important to the patient.
Choice D:Decision analytic methods are needed to help us determine whether a model is of clinical value.
Choice E:Discrimination is a property of the predictors, not the model.
Question 2: You are analyzing a training set to create a model that you intend to test on external validation sets. Which of the following is true:
Reference:Ewout W. Steyerberg, et al. Assessing the performance of prediction models: a framework for some traditional and novel measures, Epidemiology (Cambridge, Mass). 2010;21(1):128-138. doi:10.1097/EDE.0b013e3181c30fb2.
Choice A:Machine learning methods will be superior because they can take into account complex interactions and multiple variables.
Choice B:You should feel free to change the resulting model if you feel like it.
Choice C:You should feel free to modify the estimated discrimination if you feel like it.
Choice D:It is critical to assess calibration.
Choice E:It isn’t important dot every i and cross every t on the model, because you can always change it so that it fits the validation set better.
Question 3: Which of the following is true about external validation
Reference:Ewout W. Steyerberg, et al. Assessing the performance of prediction models: a framework for some traditional and novel measures, Epidemiology (Cambridge, Mass). 2010;21(1):128-138. doi:10.1097/EDE.0b013e3181c30fb2.
Choice A:If a model is externally validated on a cohort from one hospital, the results only apply to patients from that hospital.
Choice B:Once a model has been externally validated on at least one cohort, it can be widely implemented
Choice C:“There is no sell-by date on truth”: once a model has been validated, it is applicable to similar cohorts for the foreseeable future.
Choice D:Application of the results of an external validation study to a new cohort depends on careful consideration of how the new cohort compares to the cohort in the study.
Choice E:If the model does not work well on external validation, changes can be made to the coefficients or intercept: if the model then works better, the new model can be considered validated.
Question 4: The highest level of validation for a predictive model is from:
Reference:Collins GS, Reitsma JB, Altman DG, Moons KG. Transparent reporting of a multivariable prediction model for individual prognosis or diagnosis (TRIPOD): the TRIPOD statement. BMC medicine. 2015 Dec;13(1):1.
Choice A:Testing against an adequate dataset from an outside group (external validation).
Choice B:Testing against data that is set aside from the original dataset before building the model (internal validation.)
Choice C:Testing the consistency of model building by repeating the model building process on bootstrap resamples.
Choice D:Testing the predictive power of model fits by holding out data samples and testing the model on the fraction of data held out (cross-validation.)
Question 5: The problem of multiple comparisons is critical in predictive model building. Strategies to avoid over optimistic estimates of predictive power include:
Reference:Benjamini Y, Hochberg Y. Controlling the false discovery rate: a practical and powerful approach to multiple testing. Journal of the royal statistical society. Series B (Methodological). 1995 Jan 1:289-300.
Choice A:Establishing a statistical analysis plan prior to seeing the data.
Choice B:Including variable selection inside of the cross validation model fitting loop.
Choice C:In selecting variables for multi variable model fitting, adjusting p values using a false discovery rate approach.
Choice D:All of the above.
Question 6: The p value is:
Reference:Biau, D.J., et al. P value and the theory of hypothesis testing: an explanation for new researchers". Clin Orthop Relat Res. 463 (3): 885–892. doi:10.1007/s11999-009-1164-4.
Choice A:Used in the context of null hypothesis testing.
Choice B:Helps to determine the significance of your results.
Choice C:The level of marginal significance within a statistical hypothesis test representing the probability of the occurrence of a given event.
Choice D:All of the above.
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