Correction to: Eye https://doi.org/10.1038/s41433-021-01867-6, published online 05 January 2022

In part “TIP 4: UNDERSTAND SUBGROUPS”, the phrase “In our example, Study #3 only studied patients over 65 years” was corrected to read “In our example, Study #3 only studied patients who were equal and below 65 years”. The original article has been corrected.