Cohen's kappa is a measure of the degree to which 2 raters agree. There is also a test of inter-rater agreement based on kappa. Use [inter-rater] if you are interested in other aspects of IRA, but not this specific measure.

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Kappa statistic in plain English?

I am reading a data mining book and it mentioned the Kappa statistic as a means for evaluating the prediction performance of classifiers. However, I just can't understand this. I also checked ...
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4k views

Computing Cohen's Kappa variance (and standard errors)

The Kappa ($\kappa$) statistic was introduced in 1960 by Cohen [1] to measure agreement between two raters. Its variance, however, had been a source of contradictions for quite a some time. My ...
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17k views

Inter-rater reliability for ordinal or interval data

Which inter-rater reliability methods are most appropriate for ordinal or interval data? I believe that "Joint probability of agreement" or "Kappa" are designed for nominal data. Whilst "Pearson" and ...
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445 views

Inter-rater reliability with many non-overlapping raters

I have a data set of 11,000+ distinct items, each of which was classified on a nominal scale by at least 3 different raters on Amazon's Mechanical Turk. 88 different raters provided judgments for ...
4
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2answers
3k views

Assessing and testing inter-rater agreement with kappa statistic on a set of binary and Likert items?

I am trying to calculate inter-rater reliability scores for 10 survey questions (on which there were 2 raters)--seven questions are binary (yes/no), and 3 are Likert-scale questions. Should ...
4
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304 views

Is the power for a Kappa test the same as underlying z-test?

The Kappa ($\kappa$) test is a Z-test kind of test. If I am not very wrong, to compute the $\kappa$ test, we can just estimate the appropriate variance $\hat {var}(\hat\kappa)$ for the kappa statistic ...
4
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1answer
548 views

Quadratic weighted kappa versus linear weighted kappa

When should I use quadratic weighted kappa or linear weighted kappa? I have two observers evaluating the classes of a number of objects. The classes are fail, pass1, pass2, and excellent (ordinal ...
4
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1answer
157 views

Ordered category agreement

I have data on two processes, where the process assigns elements into ordered bins. I am interested in testing for agreement between the processes. What is the best way to do this (R code)? Here is ...
3
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2k views

Adjusting kappa inter-rater agreement for prevalence

I am trying to calculate kappa scores for present/absent decisions made by two raters and I have heard that they can be adjusted for prevalence of the object of measurement. Can anyone advise on how ...
3
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2answers
754 views

Inconsistency of findings between Kappa and ICC for IRR study

I used the following R script to calculate the Kappa and ICC for a measured done by two raters on 23 subjects: ...
3
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1answer
68 views

Are there good reasons to use Cohen's Kappa over Gwet's AC1?

Stats newbie here, please bear with me. I've been researching inter-rater reliability in order to figure out what I will be using for my thesis study. The most common used test for this in my ...
3
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66 views

Inter-rater agreement with different rater pairings

I have data from the following study design: 100 Patients have been examined by 2 raters each. The raters had to assign a score which consists of 7 subscores and each of this subscore consists of ...
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41 views

Is there such a thing as a multidimensional kappa test?

I am involved with designing a new diagnosis method for a routine clinical procedure. I want to compare the agreement between operators to the agreement between methods. Is there such a thing as a ...
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208 views

How do I calculate reliability between an algorithm and multiple human experts?

Compare inter-rater reliability between 8 human experts and a computer I am running a study where I use automated analysis to analyse an EEG signal (brain activity) and quantify certain properties ...
2
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1answer
5k views

ICC and Kappa totally disagree

Much has been written on the ICC and Kappa, but there seems to be disagreement on the best measures to consider. My purpose is to identify some measure which shows whether there was agreement between ...
2
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1answer
121 views

Calculating agreement between an ordinal and continuous scale

I'm having a bit of trouble wrapping my head around something. I have a data set which contains two columns that essentially attempt to measure the same thing, one on a 1-50 continuous scale and ...
2
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1answer
356 views

Limitations of Cohen's kappa for sparse data?

Are there any limitations for using Cohen's kappa with sparse data? I need inter-rater agreement between 2 raters for ~15 items, and the data in the contingency table is quite sparse (0 in some cells, ...
2
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1answer
59 views

Macro and Micro Inter-Coder/Rater Agreement

I have a labeling task with 4 labels for which I'm using 2 coders/annotators/raters. This labeling effort leads to a confusion matrix like the one in ...
2
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53 views

Fisher's exact test vs kappa analysis

I was reading a paper where the authors assessed the association between two different diagnostics tests intended to diagnose the same disease and they performed the analysis with Fisher's exact test. ...
2
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56 views

Combining different raters scores

In my experiment two raters evaluate 100 products, both expressing an "innovation score" on a likert scale (range is 1 to 5, where 1 is "not innovative" and 5 is "disruptive innovation"). I ...
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179 views

Is there an effect size for Kappa's?

I am staring a project on comparing standard ways of creating a classifier with some heuristic methods. The heuristic methods should result in a faster training for the classifier but should result in ...
2
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1answer
734 views

Sample size needed for Fleiss' Kappa?

A group of raters (about 20) will be watching a series of videos and will be classifying them into 4 categories. I will be running a Fleiss' kappa to measure the agreement. How does one compute for ...
2
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0answers
295 views

Inter-rater reliability: Nominal data, but *multiple ratings per unit/subject*, different raters

I have a data set, with each variable taking multiple values on a nominal scale. Separate raters could rate a given unit using more than one value per variable. That is, there are multiple ratings per ...
2
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170 views

Validity of grand mean intra-rater Kappa or ICC

For 5 raters, I have calculated intra-rater Cohen's Kappa statistics for the test-retest nominal ratings, intra-rater Kendall's tau-b statistics for the test-retest ordinal ratings, and intra-rater ...
2
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1answer
352 views

How should I interpret Fleiss' kappa when it equals NaN?

I noticed that when I have tables which the values are only 0 and 1, I get a kappa of 1 when the table is completely full of one, and when I have a table of zeros I get NaN as result using the irr ...
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132 views

Is it statistically correct and safe to calculate Kappa 2 test means of combinations of 2 against the value of a Fleiss' Kappa?

For my problem I have a group of p participants and s subjects. I was suggested to calculate the Kappa Cohen Test on ...
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88 views

What is currently the more accepted Agreement Between Raters Statistics or most referenced paper?

I found a question that is related here, but it doesn't really goes on what I want to know. I found a couple of papers using Kappa Statistic from 2006, and 2010, but afterwards I found other authors ...
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3answers
94 views

Is this classifier random?

I trained a classifier and got the following stats on some test data: ...
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468 views

Strange values of Cohen's kappa

I have two raters who agree on 93% on the cases (two options: yes or no). However, when calculating cohens kappa through crosstabs in spss I get really strange outcomes like -0.42 with a sig. of ...
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589 views

Quadratic weighted kappa strength of agreement

In the case of the kappa-value there are some attempts to qualify how good or bad the agreements are. For example Landis & Koch in the article The Measurement of Observer Agreement for Categorical ...
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1answer
303 views

Power analysis for inter-rater reliability study (Kappa) with multiple raters

I've spent some time looking through literature about sample size calculation for Cohen's kappa, and in several studies there are stated that increasing the number of raters, reduce the number of ...
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1answer
185 views

What are the tests to measure agreement between two methods of measurement when the unit of measurement is different between the two methods?

Bland-Altman plot measure the agreement between two different methods which measures the same variable. As far as I understand Bland-Altman can measure only if the two methods have the same unit of ...
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1answer
1k views

How to calculate error matrices, K hat and var(K hat)?

I have a very simple data set consisting of three columns: Ground Truth Canopy Class, Method 1 Canopy Class and Method 2 Canopy Class. Each row in the columns represents the canopy class (i.e. 1 ...
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1answer
41 views

Get a 95% confidence interval for Cohen's Kappa in R

I've got a study with two radiologist's reading chest x-rays and want to calculate Cohen's kappa of their agreement. The kappa2 function in the "irr" package and ...
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17 views

Combining the standard errors of Cohen's Kappa computed for multiple rater pairs

In a study on intra-rater agreement with 8 raters, I have computed Cohen's Kappa for each of the raters and I estimated the standard error of each of the kappa values using the Jackknife method. To ...
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1answer
53 views

Does Cohen's Kappa sample size calculation need a check for “true kappa” feasibility?

The sample size computation require(irr) N.cohen.kappa(rate1 = 0.9, rate2 = 0.5, k1 = 0.7, k0 = 0.5, alpha=0.05, power=0.8, twosided=FALSE) successfully runs and ...
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1answer
46 views

How to compare two Cohen's Kappa statistics based on the same sample of subjects but different raters

Suppose I have two assessment methods A and B for assessing depression. I first ask two raters (Raters 1 and 2) to use Method A to assess 50 patients. I compute Cohen's Kappa based on the ratings ...
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1answer
168 views

Cohen's Kappa using (irr) and kappa2() outputs NaN

I have calculated Cohen's Kapppa in order to assess inter-rater reliability where my data were coded by two independent raters. I used the "irr" package in R with the function kappa2(). For the ...
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1answer
34 views

How to calculate inter-rater reliability with multiple raters and multiple categories per item? [duplicate]

I have a data set for which I would like to calculate the inter-rater reliability. However, this data set does not seem to fit the typical models that conventional algorithms allow for. My data set ...
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114 views

When to use the Kappa statistic evaluation metric?

Can someone tell me when is it appropriate to use the Kappa statistic? Also why to use it when one can use Area Under the ROC curve? Or even the Area under the precision-recall curve? So what are the ...
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62 views

Kappa (interrater agreement) alternative for count-based data which results in inflated agreement at lower counts?

I have a data set where four coders are rating 800 items on various attributes. This is achieved by reporting a count of the prevalence of each attribute, e.g. rater 1 thinks attribute A appears in ...
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45 views

Observer agreement with Cohen's Kappa - is there a way to combine ratings to investigate if one rating impacts the other

I am a medical scientist doing observer agreement analysis on some very simple data using Cohen's Kappa. I have 2 observers. They score a bunch of scans on a 3 point scale for a pattern called ...
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88 views

Is Fleiss's $\kappa$ as conservative as Cohen's $\kappa$?

I know Cohen's $\kappa$ for inter-rater reliability is often regarded as a conservative estimation--e.g., Strijbos & al. below, who say The higher the number of categories, the smaller the ...
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119 views

When should I prefer kappa over accuracy for binary classification problems?

I'm using the caret package in R that provides two kind of metrics for classification problems - accuracy and kappa. When should ...
0
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1answer
138 views

How can this rating have negative Fleiss Kappa?

I am trying to calculate the Fleiss' Kappa of the following data and I got the result: ...
0
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1answer
37 views

How can I calculate percent agreement and kappa for each category?

My aim is to look at the reliability of a coding scheme which employs 7 exhaustive and mutually exclusive categories to categorise 40 "subjects" (i.e. a typical reliability study). More than 2 judges ...
0
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2answers
22 views

Cohen's Kappa, why not simple ratio

I was wondering if there is any particular reason why Cohen's Kappa is defined as this particular ration $\frac{p - r}{1 - r}$, where $p$ is the agreement rate between two, say, classifiers, and $r$ ...
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1answer
12 views

Assessing the agreement between two tests

I have genetic data. I have two tests that pick up changes in the genome (amplifications and deletions) at several different points in the DNA. There are three basic outputs- high, normal, low. I want ...
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1answer
40 views

Why does Fleiss's $\kappa$ decrease with increased response homogeneity?

The Fleiss method for computing inter-rater agreement seems like a great measure for computing agreement among multiple raters, in terms of agreement by chance. However, I've noticed that when ...
0
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1answer
1k views

What is the intuition behind the Kappa statistical value in classification

I understand the formula behind the Kappa statistic value and how to calculate the O and E value from a confusion matrix. My question is what is the intuition behind this measure? Why does it work so ...