# What is a good C index?

## What is a good C index?

The C-statistic (sometimes called the “concordance” statistic or C-index) is a measure of goodness of fit for binary outcomes in a logistic regression model. A value of 0.5 means that the model is no better than predicting an outcome than random chance. Values over 0.7 indicate a good model.

## How do you interpret Cox model coefficients?

The coefficients in a Cox regression relate to hazard; a positive coefficient indicates a worse prognosis and a negative coefficient indicates a protective effect of the variable with which it is associated.

What is a C in statistics?

P (AB) indicates the probability that events A and B will occur. You can write that P (A∩B). The header c stands for complement and Ac stands for all results that are not in A.

What is the C statistic?

The C statistic is interpreted as the probabil- ity that a randomly selected subject who experienced the outcome will have a higher predicted probability of having the outcome occur than a randomly selected subject who did not experience the outcome.

### What does Cox regression tell?

Cox’s proportional hazards regression model (also called Cox regression or Cox’s model) builds a survival function which tells you probability a certain event (e.g. death) happens at a particular time t. Once you’ve built the model from observed values, it can then be used to make predictions for new inputs.

### What is the difference between Kaplan Meier and Cox regression?

Kaplan–Meier provides a method for estimating the survival curve, the log rank test provides a statistical comparison of two groups, and Cox’s proportional hazards model allows additional covariates to be included. Both of the latter two methods assume that the hazard ratio comparing two groups is constant over time.

How do you calculate C in statistics?

The c-statistic is equal to the AUC (area under the curve), and can also be calculated by taking all possible pairs of individuals consisting of one individual who experienced a positive outcome and one individual who experienced a negative outcome.

What is C value in statistics?

#### How to compute Harrel’s C index for a Cox model?

Computes Harrel’s C index for predictions from a “coxnet” object. a survival response object – a matrix with two columns “time” and “status”; see documentation for “glmnet”

#### How to compute the concordance index for a Cox model?

Computes the concordance index, taking into account censoring. Harrel Jr, F. E. and Lee, K. L. and Mark, D. B. (1996) Tutorial in biostatistics: multivariable prognostic models: issues in developing models, evaluating assumptions and adequacy, and measuring and reducing error, Statistics in Medicine, 15, pages 361–387.

How to use rcorr.cens ( ) with Cox model?

#I’ve seen people mention `rcorr.cens ()`, but I can’t figure out a way to use #`rcorr.cens ()` with a Cox model of several variables. I appreciate your help! I just got an explanation from a colleague about how to use this feature. In the help page for rcorr.cens (), it states that x is a “numeric predictor variable”.

How to calculate dxy and C-index in RMS?

I can successfully use validate () in the rms package to calculate the Dxy and c-index for my boot-strapped internal validation. Now I need a c-index for my external validation.