What is the test for "abuse of discretion" in sentencing sentencing sentences?

We review sentences "under an abuse-of-discretion standard" for both procedural and substantive unfairness. Gall v. United States, ___ U.S. ___, 128 S.Ct. 586, 597, 169 L.Ed.2d 445 (2007). With regard to procedural unfairness, we will find an abuse of discretion where the district court "fail[ed] to calculate (or improperly calculat[ed]) the Guidelines range, treat[ed] the Guidelines as mandatory, fail[ed] to consider the 3553(a) factors, select[ed] a sentence based on clearly erroneous facts, or fail[ed] to adequately explain the chosen sentence." Id.