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rwg(J), r*wg(J), AD and ICC(1)/ICC(2) Calculator for Team and Climate Data

How do you calculate rwg(J)?

rwg(J) = J(1 - s̄²/σ²E) / [J(1 - s̄²/σ²E) + s̄²/σ²E], where J is the number of items, s̄² the mean of the item variances within the group, and σ²E the variance expected if responses were random: (A² - 1)/12 for A response options (2.00 on a 5-point scale). Values of .70 or more are conventionally taken to support aggregation, together with ICC(1) and ICC(2).

Every thesis that turns individual ratings into a team or organisational score has to justify it with rwg and ICCs, and until now that meant installing R. Paste the data here instead.

One line per respondent with their group and item responses; the calculator gives rwg(J), r*wg(J) and AD for every group, and ICC(1) and ICC(2) across groups.

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Built by Muhammad Shahzeb Anwar, MSc Industrial and Organizational Psychology. Multilevel aggregation is routine in I/O and organisational research on climate, culture and team processes.

The calculator

Your data

Runs in your browser. Nothing you type is stored or sent anywhere.

5 for a 1-5 scale, 7 for 1-7.
Example data are filled in; replace them. Use the items of one scale only. Nothing you paste leaves this page.

Which index, for what

rwg(J) (James, Demaree and Wolf, 1984) is the standard agreement index; when observed variance exceeds the null variance it is set to 0, which can hide real disagreement. r*wg(J) (Lindell, Brandt and Whitney, 1999) does not use the Spearman-Brown adjustment and can go negative, which shows polarised groups. AD, the average deviation (Burke, Finkelstein and Dusig, 1999), is in the units of the scale; Burke and Dunlap (2002) suggest agreement when AD is at or below A/6 (0.83 on a 5-point scale). ICC(1) is the share of variance due to group membership and ICC(2) the reliability of the group means (Bliese, 2000).

The uniform null assumes no response bias. If responses lean towards one end for reasons unrelated to agreement (social desirability, leniency), a skewed null with smaller variance is more honest; enter its category probabilities and the calculator uses its variance instead.

About the .70 rule

The .70 cut-off for rwg is a convention, and O'Neill (2017) traced it to a personal communication rather than a derivation. LeBreton and Senter (2008) recommend reporting values in bands and with the null distribution stated, and Dunlap, Burke and Smith-Crowe (2003) give significance tests by simulation. Report the median and the range across groups, not only how many pass.

Before you rely on this

What this will not tell you

This computes the indices from the data you paste, using one scale at a time. It does not run the simulation-based significance tests, does not handle missing responses (remove incomplete rows), and computes ICC(1) with the mean group size, as the R multilevel package does; with very unequal groups an adjusted group size gives a slightly different value. Nothing you paste leaves your browser.

Questions

Questions people actually ask

What is a good rwg value?

By convention .70 or above is taken to support aggregation, but that cut-off has no statistical basis. Report the median and range across groups and the null distribution you used.

What is the difference between ICC(1) and ICC(2)?

ICC(1) is the proportion of variance in individual responses explained by group membership. ICC(2) is the reliability of the group means, which rises with group size.

What null distribution should I use for rwg?

The uniform null, with variance (A squared - 1) / 12, is the default. If you have reason to expect response bias such as leniency, a skewed null with smaller variance gives more conservative values.

What is r*wg(J)?

Lindell, Brandt and Whitney's (1999) version, 1 minus the ratio of mean observed variance to null variance. Unlike rwg(J), it can be negative, which signals disagreement stronger than random responding.

Why is my rwg(J) zero?

Because the observed item variance in that group is larger than the null variance, and rwg(J) is conventionally truncated to 0 in that case. Look at r*wg(J) to see how strong the disagreement is.

The papers behind the method

Sources

Each reference was checked against its DOI record on 17 October 2026. Bliese (2000), the book chapter on within-group agreement and ICCs, has no DOI.

  1. James, L. R., Demaree, R. G., & Wolf, G. (1984). Estimating within-group interrater reliability with and without response bias. Journal of Applied Psychology, 69(1), 85-98: https://doi.org/10.1037/0021-9010.69.1.85
  2. Lindell, M. K., Brandt, C. J., & Whitney, D. J. (1999). A revised index of interrater agreement for multi-item ratings of a single target. Applied Psychological Measurement, 23(2), 127-135: https://doi.org/10.1177/01466219922031257
  3. Burke, M. J., & Dunlap, W. P. (2002). Estimating interrater agreement with the average deviation index. Organizational Research Methods, 5(2), 159-172: https://doi.org/10.1177/1094428102005002002
  4. Dunlap, W. P., Burke, M. J., & Smith-Crowe, K. (2003). Accurate tests of statistical significance for rWG and average deviation interrater agreement indexes. Journal of Applied Psychology, 88(2), 356-362: https://doi.org/10.1037/0021-9010.88.2.356
  5. LeBreton, J. M., & Senter, J. L. (2008). Answers to 20 questions about interrater reliability and interrater agreement. Organizational Research Methods, 11(4), 815-852: https://doi.org/10.1177/1094428106296642
  6. O'Neill, T. A. (2017). An overview of interrater agreement on Likert scales for researchers and practitioners. Frontiers in Psychology, 8, 777: https://doi.org/10.3389/fpsyg.2017.00777
Citation

Cite this tool

Free to use and free to quote. If a figure here is useful in something you are writing, a link back is all that is asked.

Muhammad Shahzeb Anwar, MSc Industrial and Organizational Psychology. rwg and ICC Calculator (Within-Group Agreement). Shahzeb Speaks. https://www.shahzebspeaks.com/rwg-icc-calculator/

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