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# 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.

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23 views

### Concordance of an ordinal time series

I have panel data with an ordinal outcome that was assessed by two independent reviewers - i.e. each is unaware of the others' assessment. The time points for assessment are not necessarily concurrent,...
1 vote
84 views

### Statistical test to compare models results for concordance index

I'm working on a model for survival prediction and using the concordance index to evaluate the results (https://medium.com/analytics-vidhya/concordance-index-72298c11eac7) . I want to show that my ...
20 views

### Do we expect sorted or unshuffled single variable outcomes to be the cause, a mere artifact, or generally prevalent?

Forgive me if this is a high school AP level theorem, my last stats class, but how can we treat upon a y-axis outcome an endogenous exogenous cause from an unnecessary but sufficient artifact. A (1) ...
115 views

### compare Lin's concordance correlation coefficients of two different groups

i have two study groups where Lin's concordance correlation coefficient between two continous variables (eg. weight and hight) were calculated for each group. Concordance correlation coefficent for ...
14 views

### Why is my concordance measure greater than 1?

I've written a function to assess the coefficient of concordance for vague data. I'm using it to measure consistency in the rank order of some items ranked by two reviewers. It's vague because each ...
32 views

### Calculating the integrated prediction error curve

I am reading Tutz & Schmid "Modeling Discrete Time-to-Event Data" (2016) chapter 4 Evaluation and Model Choice section 4.3.2 Prediction Error Curves. Integrated prediction error curve is ...
44 views

### Lin’s concordance correlation coefficient is low but numbers are close. Any reasons?

I am working out Lin’s concordance correlation coefficient (CCC) for incidence and prevalence between two methods for different diseases. For most of my comparisons i get a high CCC of arouynd 0.95. ...
1 vote
70 views

### Concordance Correlation Coefficient for negative correlations

A question regarding the Concordance correlation coefficient (CCC). I would like to implement it in Python. Following the Wikipedia entry, one of the possible implementations would be ...
49 views

### Determine cause of poor concordance index?

I have a survival dataset which I’ve experimented with to create several Cox PH models using different techniques (lasso, forward selection, backwards elimination etc), however no matter which ...
128 views

### Extension of the relationship between ROCAUC/c-index and Wilcoxon-Mann-Whitney U

There is a relationship between ROCAUC and the Wilcoxon Mann-Whitney U test of the probability predictions of the two groups. If our $y$ variable has more than two classes, can we extend this to a ...
465 views

### How to interpret time-varying AUC for Survival Analysis?

I have trained some models for survival forecast (only interested in ranking of observations). I obtained C-index values as well as dynamic AUC values for the three trained models (CPH, AFT -weibull- ...
325 views

### Why does random survival forest use Cumulative Hazard Function to calculate C Index?

I am working with Random Survival Forests and I found out in the documentation that it uses Sum of Cumulative Hazard Function to define a worse predicted outcome, which is subsequently used to compute ...
141 views

### Comparison of experimental method against gold standard?

I have a method X, assumed to be the gold standard. Then, I have a method Y. The response variable (for example, weight) is a continuous variable. For a sample of n individuals, the response variable ...
986 views

### Customized concordance index for survival analysis in python

I am trying to build a two-stage model where I classify my data and split it into two datasets. I then fit a Cox Proportional Hazard model to each dataset and make predictions and can calculate the C-...
705 views

### Evaluating fitness of CoxPH survival regression model with Concordance-index

I'm doing a survival analysis for cancer patients. I have two different models for two different types of cancer (different datasets). Some key differences between model 1 and 2 are: Model 1 has only ...
1 vote
132 views

### Concordance estimate survival data in long format

I would like to use concordance to have an idea of my models discrimination power. Because I have time dependent covariates, the time to event data is in a "long" format, i.e. one row per ...
1 vote
160 views

### Concordance correlation always less than or equal to pearson correlation

Can someone explain intuitively (or even mathematically) why Lin's concordance correlation coefficient (CCC) is always less than or equal to pearson's correlation coefficient (PCC). A related query ...
1 vote
51 views

### Is it necessary to do multiple hypothesis testing for AUC comparison? [closed]

Dear all: Is it necessary to do multiple hypothesis testing for AUC comparison. For example, if I calculate AUC from logistic regression, there is an AUC value. As we know, we can compare two models ...
108 views

### Can you have a concordance statistic (discrimination) when predicting a continuous outcome?

I'm writing a proposal for a prediction model predicting BP (continuous outcome, predicting trend over time). For assessing model performance, I'm seeing discrimination and calibration as the most ...
1 vote
72 views

### circular ranked lists

I have two lists which are circular, in that given list ['A','B','C','D','E'] 'A' and 'E' are the same distance apart as 'A' and 'B' and so on. Given I have rankings R1=['A','B','C','D','E'] R2=['...
1 vote
98 views

### Cohen's kappa and confounders

I'm interested in how certain factors affect the inter-rater reliability of two driving examiners (sitting in the back seats) in deciding whether to pass or fail the examinee. For example, age, ...
159 views

### Does a high negative concordance imply reproducible features

Does a high negative(-1) Lin's concordance correlation coefficient(Lins CCC) imply reproducible features ? I am calculating Lin's CCC of radiomic features between two different CT scan settings , ...
209 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 ...
620 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 ...
2k 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 ...
1k 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 ...
238 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 ...
10k 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: ...
314 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: ...
2k 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 ...
2k 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?
6k 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 ...
433 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 ...
2k 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 ...
800 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 ...
109 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 ...
135 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 ...
93 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 ...
316 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 ...
1 vote
50 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 ...
411 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'...
2k 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 ...
1 vote
163 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 ...
5k 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 ...
337 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 ...
986 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 ...
1 vote
445 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 ...