Questions tagged [concordance]

Concordance measures the level of agreement when different raters or judges are evaluating the same units. Many different measures of concordance exist, some of them are Krippendortff's alpha and Cohen's kappa. ICC intraclass correlation coefficients are closely related.

31 questions
15 views

is the concordance (c-index) appropriate for negative binomial and Poisson regression

I understand it's mainly used for binary logistic regression, according to the rms package I'm using to calculate it. I've come across a single source that used the c-index for negative binomial ...
19 views

Somers' D deteriorating for more granular rankings

Background I have 30 observations and I want to compare how much experts and model agree with each other. For Model and Expert I have slots which are $\in [1,4]$ and ranking which are $\in [1,30]$. ...
75 views

What are the pros and cons of different metrics for evaluating a logistic regression model?

In the data science world, I have always evaluated the performance of logistic regression models simply using ROC/AUC. However recently, I've read from some traditional statistics source about some ...
236 views

Theoretical computation Kendall's tau [closed]

While working with rank correlation statistics of samples, specifically Spearman's rho and Kendall's tau, I came across the interesting theoretical interpretation of Kendall's tau. It can be viewed as ...
300 views

Use median survival time to calculate CPH c-statistic?

I'm interested in calculating the concordance ($c$-statistic) of a proportional hazards model. For reference, the c-statistic is detailed in Stat Med. 1996 Feb 28;15(4):361-87. The relevant quote ...
398 views

Correct interpretation of Kendall's W

This is a follow-up to my earlier question. Let me summarise what the original question dealt with. I asked whether I could compute Kendall's W for a case where the same question was asked for ...
102 views

Kendall's W for a series of answers about the same phenomenon in different entities

I have a question about the proper usage of Kendall's coefficient of concordance (Kendall's W). Suppose a series of questions were asked how democratic certain organisations are. Each question was the ...
3k views

How to interpret concordance index in Cox models?

I'm new using the survival package in R. Consider an example provided with the package: ...
128 views

How to manually calculate concordance for a coxPH model

I am struggling to work out how the concordance statistic of a coxPH model is derived. I have built a coxPH model on a small dataset (4 observations). The resultant model is given below: ...
558 views

What is the right measure to compare survival models?

Suppose that there are N patients indexed by n = 1, 2, ..., N. Suppose that I estimate two different survival models M1 and M2. Model $i$ gives a risk score $r_n^i$ for patient $n$. According to ...
460 views

AUC/C-index confidence interval estimate

Is there a way to compute an estimate of the AUC/C-index confidence interval, simply by using a mean AUC/C-index and sample size?
3k views

How does AUC of ROC equal concordance probability? [duplicate]

If this answer on Quora is correct then I think I understand what concordance probability is. However, I also find that this answer on StackExchange provides the formula of concordance probability ...
180 views

How to calculate the standard deviation of the C-index?

I fitted a coxph model and below is the concordance details from my object named cx. I can see that ...
1k views

Concordance index in survival and rms packages

I would like to compute concordance index to validate Cox model. From the following post concordance rms I know that I can use rms package and ...
248 views

How to calculate concordant percentage in a validation data

I've created a logistic regression model in R using the glm function using a bank data and. I am able to get the AIC value, coefficients, percentage concordant, tied and discordant pairs in test and ...
89 views

using non-cancerous patients to predict survival time from cancer?

I have data that consists of lab test results for patients, cancer dates for those who got cancer, and time till death/censor from that cancer. This cancer is both rare (most of the patients never get ...
93 views

Kendall W for continuous data

Simple question: can I use the Kendall W test for continuous data? Cuz I used it for a bunch of continuous variables and almost all coefficients are very close to 1, with p-values very very very small ...
86 views

Is it normal for logistic regression, to have predictors which have good Wald's Chi Sq, but still bad performance?

I have trying to build a logistic model with some 10 variables. All of those variables have Wald Chi sq value<500. All are highly significant p-value<0.0001. Event rate is about 3%. The ...
251 views

classification for concordance index

In this paper (and in most of the others I found), the authors want to find a continuous predictor that maximizes the concordance index. I would like to have a binary classifier instead that ...
42 views

Can Cohen's kappa be used for raters with different but related targets?

There are two binary raters: Rater 1 is certified to assess the ability of people to drive a taxi. Rater 2 is certified to assess the ability of people to drive a lorry. Rater 1 and 2 have both ...
3k views

How to compare predictive power of survival models?

Frank Harrell describes the concordance (or Somer's D) as not being sensitive enough to compare multiple survival models for their diagnostic ability, and I've observed this in my own work with ...
205 views

Interpreting a concordance < 0.5 in survival analysis

I've seen it detailed that a concordance of < 0.5 can be viewed as a measure of better than random predictive power, similarily to the AUC. When a classifier obtains an AUC of 0.2, you know that it'...
1k views

Inter-(-intra) class correlation coefficient or intra-(inter-) concordance coefficient in python

My question is about how to calculate inter-(intra-) class correlation coefficient (ICC) or intra-(inter-) concordance coefficient (CCC), ideally in python. My dataset consists of several dozen ...
99 views

Cox regression covariate specific concordance independent of distribution of covariates in sample?

Concordance seems to be a very good metric for telling you how well the model allows you to order individuals for the particular sample that is being used. However, when applying a cox regression ...
2k views

Bland-Altman (Tukey Mean-Difference) plot for differing scales

I find that Bland-Altman plots for comparing two methods are extremely useful in assessing agreement. However, I'm curious if there is a similar method or transformation that can be used when the ...
232 views

Quantifying consistency between two groups of raters

I have two groups of people, group A (62 people) and group B (8 people), and each person in each group responded to a test with the same 8 questions where the answer to each question was one of the ...
500 views

Does concordance correlation require data to be normally distributed?

I would like to know if the results from Device 'A' and Device 'B' are in agreement when measuring the same thing. I have 258 pairs of results. The results are interval variables and have the same ...
218 views

How does a discordance test work?

Could someone explain how the discordance test works (and what it actually is)? The explanations I found online are unclear: [...] the concordance test can be viewed as the evaluation of the ...
176 views

C-statistic for comparison of incidence rate poisson to cumulative incidence logistic models

I'm looking to compare the capacity of two models for predicting who does, and who does not, develop a certain infection during a hospital stay. Both models are based on the exact same patients, but ...