April 6, Translating science problems. to statistical questions : some challenges and examples. Constantine Frangakis. 1.

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Elwin Collins
5 years ago
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1 s : s : April 6, 2015

2 s : experiences based on collaborations with the Depts of Radiology (JF Geschwind) and Psychiatry (C Lyketsos)

3 s : Accuracy of translation Accuracy of translation of a scientific usually requires placing the within a larger hypothetical framework than the one accessible (design choices, data types etc). Decidability can trade-off against accuracy given the accessible framework This trade-off affects and can lead to poor choice of the statistical the design the methods

4 s : Medical : Liver cancer is assessed by many staging systems. How do we compare their value in predicting survival? Design of accessible data: Cohort [JHH]; Georgiades, CS, Liapi, E,, CE, Park, J, Kim, HW, Hong, K, and Geschwind, JFH (2006). J Vasc Interv Radiol 17, (with discussion in 18, )

5 s : Translation of medical : How do we assess (a) the value (b) of a staging system in predicting survival (c)? Observations: to predict survival (c), we need to say how we would value (b) it. if the outcome is fully observed, the literature usually uses R 1 or R 2 for the value of a predictor but if the outcome is censored, the literature usually uses a model-based value (e.g., based on Cox regr). this is because the assessment (a) is more difficult with censoring can we keep a clinically meaningful value (b), and change the way of assessment (a)?

6 s : Medical : A clinical trial showed a treatment vs usual care (placebo) benefit. Also, among patients who had responded after 3 weeks on placebo, 68% remained responders at week 9; whereas of the patients who had not responded at 3 weeks on placebo, only 10% responded at week 9. Can we estimate the benefit that patients who do not respond after 3 wks of placebo would have after 9 more wks on treatment? Design of accessible data: 3, 9 week data of response for patients in each of treatment/placebo group Porsteinsson et al. (2014). JAMA 311, (with editorial)

7 s : Translation of medical : what is the benefit that patients who do not respond after 3 wks of placebo would have after 9 more wks on treatment? Observations: understanding the needs an expanded framework that did not occur in the trial: to consider patients who do not respond under 3 wks placebo, then assign them to treatment/placebo and measure the outcome after 9 wks.

8 s : Translation of medical : Can we estimate the benefit focusing on patients who do not respond after 3 wks of placebo? Observations: we consider instead the outcomes at week 9, say 9t, that a person who has factually been assigned to placebo and did no respond (3p = 0) would have had if, contrary to fact, that person had originally been assigned to treatment. what would be a usual approach to estimate the benefit for these patients? can we use a different that does not make the assumption of the usual method?

9 s :

10 s : Medical (context as before) What sample size would we need to test for benefit in a 3wk placebo runin + 9 wk experiment trial? Design of accessible data: 3, 9 week data of response for patients in each of treatment/placebo group

11 s : Translation of medical : What sample size would we need to test for benefit in a 3wk placebo runin + 9 wk experiment trial Observations: the answers differ by a 3-fold depending on what translation to statistical is used

Table S1. Reclassification of 5-year risk of all-cause mortality among colorectal cancer patients by continuous E-cadherin (n=188)

Table S1. Reclassification of 5-year risk of all-cause mortality among colorectal cancer patients by continuous E-cadherin (n=188) Diagnostic Accuracy and Prediction Increment of Markers of Epithelial-Mesenchymal Transition to Assess Cancer Cell Detachment from Primary Tumors BMC Cancer Evan L. Busch, Prabhani Kuruppumullage Don,