perspective—being independent of the size of an institution. This distinction is particularly relevant when reporting correlations.

3.  Correlations between metrics and peer review may not be the most informative measure of agreement. Other measures may be more appropriate.

4.  Peer review is subject to uncertainty. This should be taken into consideration when interpreting the agreement between metrics and peer review.

We first briefly discuss the REF and consider its objectives. This is followed by a review of the literature on comparing metrics and peer review in the context of the REF and its precursors. We argue that in the REF context, proper comparisons between metrics and peer review should be made at the institutional level, not at the level of individual publications. We also briefly discuss how a size-dependent perspective relates to a size-independent perspective. As we show, size-dependent correlations can be high even if the corresponding size-independent correlations are low. We then introduce two measures of agreement that we consider to be more informative than correlations. One measure is especially suitable for the size-dependent perspective, while the other measure is more suitable for the size-independent perspective. To get some idea of the uncertainty in peer review, we introduce a 