Leonardo Frazzoni

5 Questions 6 Answers 0 Followers

Questions related from Leonardo Frazzoni

Can I get help with predictive model with quasi-complete separation?

Hi all, I am running a logistic regression in R with 5 independent variables, and I get strange OR values when I ask R to exponentiate coefficients (e.g. 8.739675e-01). I read that this might be...

06 June 2015 8,886 8 View

How do I get the sample size for non-inferiority and equivalence trials with TrialSize package in R?

I am trying to get two sample sizes (treatment vs. control) for differences in proportions (e.g. 80% vs. 70% of success), for non-inferiority and equivalence trials with R-package TrialSize....

04 April 2015 1,631 4 View

Are large upper 95% values for Odds Ratios correct in logistic regression?

I am dealing with a logistic regression with quasi-complete separation. I used Firth's logistic regression to deal with this, and everything seems to be right, except that I have two predictors...

03 March 2015 343 5 View

Is there a way to make a bubble plot in metaregression with the metafor package?

I made a metaregression with "metafor" package for R, and I would like to make a bubble plot too to show the direct relationship between the predictor and the outcome. Unfortunately, I still...

03 March 2015 2,160 2 View

How can I compare positive and negative predictive values, and likelihood ratios, of two different diagnostic tests in an unpaired design?

The two diagnostic tests have categorical response (i.e. cancer yes/no). Is it correct to use the Z test to compare positive and negative predictive values, and likelihood ratios, if I consider...

02 February 2015 4,856 5 View