The Intra-class Correlation Coefficient measures the degree to which a categorical variable accounts for variability in a continuous variable. It is often used to index the degree of clustering in a dataset.

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'irr' R Package giving ICC values outside of 0 - 1

I ran a study looking at MEG (EEG with magnets) responses in the gamma-band (30-50Hz) range across multiple days. The following data is the timing of the initial response in that range (in seconds), ...
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15 views

How to analyse individual consistency from three non-normally distributed variables?

I would like to know if individuals were consistent across three different days. I measured the latency of individuals for a maximum of ten minutes. Many individuals had a latency of 0 and some ...
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17 views

Computing the Correlation with Skewed Repeated Measures Data

Suppose I have two variables (e.g., Blood Pressure and Cholesterol) and I want to investigate their association across time. Also suppose that each individual has been measured three times ...
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6 views

Reliability Measure for Unequal Subjects between Raters?

I am comparing two medical imaging analysis techniques, and I would like to assess the inter- and intra-rater reliability for using each method. I am planning the study design, and would like help ...
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1answer
55 views

Can ICC values be negative?

I am calculating the ICC as per the method of Shrout-Fleiss (1979), using the (3, 1) model in which the judges are fixed as are the targets. Some of my ICC values are negative. Is this to be ...
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25 views

Intraclass correlation coefficient: mean of raters, or better rater?

Suppose I have a set of stimulus, that was rated by three independent rater. I then estimated the Intraclass correlation coefficient, with a resulting value of 0.881. Let's consider a practical ...
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10 views

correlate/compare two scales measuring different constructs

I need to compare a multidimensional pain scale item response >3 pain is present and a scale measuring emotional suffering with classified levels of suffering (High, intermediate and low). Will ICC ...
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37 views

Likert scale inter rater agreement

What is the best inter rater agreement test for Likert scale type questions. As far I saw that cronbach alpha is for internal consistency, or it shows how good items are related to describe the main ...
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43 views

Correlated predictors in linear model: where does shared variance go?

I analyze a dataset consisting of responses to two conditions with a multiple regression analysis. I dummy code the two conditions to retrieve the contribution of each of them to the data. Up to here, ...
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24 views

Measure of accuracy or measure of agreement for continuous data with true values

I have two continuous variables. Variable $X$ represents the true values (basically it is atmospheric pressure measured via a barometer). Variable $Y$ represents a way to approximate the atmospheric ...
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48 views

Intraclass Correlation Coefficient Confusion

Many times in statistics we are using a statistic in different ways. I think Intraclass correlation coefficient is one of them... Intraclass Correlation Coefficient can be a A) measure of inter-rater ...
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5 views

Assessing test-retest reliability of a questionnaire [duplicate]

I am testing the test-reliability of a newly developed questionnaire over two time points. The study involves parents answering about their child over the two occasions. Would intraclass correlation ...
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1answer
25 views

Statistic to find out association between ordinal data

I have a 4x3 contigency table with ordinal data for a research finding in tuberculosis, I analysed cytology patterns and afb patterns; cytological pattern $A,B,C,D$ (independent variable) and afb ...
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51 views

What is a “subject” in ICC?

I have been working in R and have finally got some code working regarding intraclass correlation coefficients. In the output I get something called "subjects". I thought it was to do with the number ...
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69 views

Mean pairwise Pearson correlation

Consider a set of $M$ multidimensional observations $X=\{x_i\}_{i=1..M}$ for $x_i\in\mathbb{R}^N$, and define $c_{ij}$ to be the Pearson correlation coefficient between $x_i$ and $x_j$. Is there a ...
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1answer
35 views

Comparison between fat-matrix

I have two data sets obtained from two different kind of chemical analysis: GC-MS and IR. Both the chemical analysis were performed using the same samples. My aim is to know if there are some ...
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1answer
156 views

ICC in a linear mixed model - longnitudial data - why is this the correlation between time periods?

I'm confused by the description of the intraclass correlation (ICC) for a linear mixed model with longitudinal data from this material. A screen capture is shown below. What I'm confused about is ...
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70 views

Intraclass correlation (ICC) per item instead of across items

I am using the intraclass correlation coefficiant to determine inter-rater reliability for a set of pictures that were rated by several raters on a scale from 1-9. I am using the two-way mixed model ...
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1answer
85 views

Measuring intra-observer correlation

We're far from what you'd call expert statisticians, so we'd like to ask some help in an ongoing medical research. We have 60 subjects. A researcher took at least 3 times the measurements of 8 of ...
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1answer
291 views

How to compare repeatability (ICC) of different groups?

I have calculated the ICC values for two groups and would now like to compare the ICC values to determine if the groups differ in their repeatability. In the literature people have simply used t-tests ...
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204 views

Intra- and inter- observer error, and the intra-class correlation coefficient (ICC)

I have 3 observers, who each perform multiple observations in which they count a phenomenon. I'm trying to quantify both inter- and intra- observer error for this study. I'm new to this and am finding ...
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1answer
103 views

ICC - unclear comment from reviewer

I'm new here and not a statistician, so I apologize in advance and I sure hope someone can help! I'm working on a study where we have 10 locations $(5 \ intervention, 5 \ control)$. We have two ...
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1answer
121 views

Low intraclass correlation although between variance is very high in random effects model

I don't understand why a random effects model can give you a very low rho (intraclass correlation coefficient), if the between variance (between subjects) in your ...
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182 views

How to analyze intra-rater reliability with 31 raters who all rated 4 subjects twice

I'm trying to analyze the intra-rater reliability of an occupational therapy assessment. The assessment consists of 57 items, where some items are ratio data and some items are ordinal data. In my ...
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45 views

Averaging correlation matrices among subjects

Suppose I have N correlation coefficient matrices, containing the Pearson correlation coefficients of k different time series of ...
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25 views

Combining critic scores into single rating

I have a collection of scores from critics for various restaurants. Some restaurants are rated by multiple critics and some by only a single critic. Each critic rates restaurants using different ...
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1answer
110 views

Agreement of clustered data

I have the following situation: I have analyzed several data curves from a group of patients (16 curves per patient) with different analysis methods and want to test for the agreement of the methods. ...
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324 views

how to partition the variance explained at group level and individual level

Based on results of Null model, some scholars suggest variance attributed to group level and individual level is computed using variance component output, whereas other suggest going the standard ...
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1answer
802 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 ...
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127 views

Comparing two dependent intra-class correlations (ICCs)

We are measuring two waves from a biological signal. As an example consider the ECG $P$ wave and $T$ wave. From a single trace, the amplitude of both of these waves is measured. We want to compare ...
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228 views

Intraclass correlation in the context of linear mixed-effects model

Suppose that one investigates the two sources of variability with data $y_{ij}$ acquired from $j$th subject under $i$th session ($i=1,2; j=1,2..., n$). A linear mixed-effects model can be formulated ...
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123 views

intra-rater reliability and assessment error - which ICC type to use? singular rater

I'm trying to figure out which ICC type to use to calculate MY measurement error using a particular assessment tool: background and data: PhD feasibility phase only. 10 pairs of videos of people ...
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98 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 ...
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1answer
65 views

Looking for simple examples of how to calculate type III and type IV SS

I have data collected on five species of fish at half a dozen locations in a lake over four years. The categories are not (at all) fully crossed, and I have a lot of empty cells due to logistical ...
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2answers
517 views

Looking for Intuition Regarding Fixed/Random Effect Conundrum

I understand that we use random effects (or mixed effects) models when we believe that some model parameter(s) vary randomly across some grouping factor. I have a desire to fit a model where the ...
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2answers
509 views

What statistics should I use for evaluating the accuracy of predictions?

I have two variables representing 1) players' predicted fantasy football points and 2) players' actual fantasy football points scored. What statistics are best for assessing the accuracy of the ...
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406 views

Computing Cronbach's Alpha and Intraclass Correlation coefficient from an lmer model

I am trying to calculate the Intraclass Correlation for a rater study using R and the library lme4 and the function lmer. The data has the following design: The same 6 raters (at least 4) are rating ...
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2answers
659 views

Several intraclass correlations (ICC) when modeling heterogeneous variances?

In a nested design (e.g., students in schools, ants in colonies, individuals in a species, leaves in a tree), ICC is defined as the proportion of variance among observations from the same subject ...
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82 views

Assessing the ability of two quantitative methods measuring the same thing

Suppose I have two scientific approaches to measuring the same physical quantity taking values between $[0,1]$. One (say method A) is generally accepted to be more accurate under certain conditions, ...
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1k views

For intraclass correlation coefficients (ICC), interpret both “single” and “average” measured ICC values for reproducibility test?

Say there's a new machine for use in testing a biochemical marker's concentration in the blood, and we would like to know the reproducibility of this test. We draw blood samples from 10 volunteers, ...
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1answer
628 views

Intraclass correlation coefficient, non parametric data

Does the ICC require that my data are normally distributed? If more information about my data is needed, just ask.
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110 views

Intrarater reliability

I would like to estimate the intrarater reliability in a MRI study. Different regions of interest were manually traced with a mouse-driven cursor in order to estimate their volumes. All data were ...
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2answers
442 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: ...
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255 views

What GEE-exchangeable method can do that robust variance can't?

I asked a related question before here on the difference between GEE method with exchangeable varcov structure v. Robust standard errors known as Huber White method in group randomized trials. As ...
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1answer
536 views

How to statistically test whether there is any nesting effect in the data?

I have a sample including all students within 52 schools which have been randomly assigned to be treatment or control (we have group randomized trial in which all students in each school is either ...
7
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1answer
867 views

How to perform inter-rater reliability with multiple raters, different raters per participant, and possible changes over time?

Participants were rated twice, with the 2 ratings separated by 3 years. For most participants the ratings were done by different raters, but for some (< 10%) the same rater performed both ratings. ...
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347 views

Nonparametric ICC

Anyone can suggest me a nonparametric version of the intraclass correlation coefficient (ICC)? My model have the following details: two-way random effects model, consistency, average ratings as unit. ...
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113 views

Intraclass correlation to validate a measure

I would like to understand whether the output of an algorithm I developed agrees with the ratings of external observers. The number of observers is 10 and each of them rated on 2 3-point-Likert items ...
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164 views

Within group correlation of pearson's residuals

I have social network data in which an "ego" names a friend "alter". I am running a regression in R in which attributes of alter are predictors of outcomes for ego. So each observation is dyadic with ...
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1answer
2k views

Justification of aggregation in multi-level model - ICC in SPSS

I am running a multi-level model on data which is set out with one row per individual survey return, each with Individual ID and Organisational ID as columns. There are variables which can be ...