Hello Anna,

Tukey's 5-number summary works well to describe succinctly both symmetric and asymmetric distributions: Minimum, Lower hinge, Median, Upper hinge, Maximum value comprise the 5 numbers.

While Lower hinge and Upper hinge have slightly different definitions than Q1 (or 25th percentile point) and Q3 (or 75th percentile point) respectively, they are very close. All of which is to say that IQR will always work to capture middle 50% of cases, whereas Mean +/- 0.67 SDs only works to capture middle 50% in normal distributions.

Good luck with your work.