This is an appeal by a mother and her eight-year-old child from a finding by the trial judge that the mother had abused and neglected her child under D.C.Code § 16-2301(9)(A) (1981). The judge based his finding of neglect on the fact that the mother had beaten the child with a belt notwithstanding her knowledge of the child’s severe psychological problems when the child had denied setting fire to her bed. Appellants contend that the key findings of fact are unsupported by the record, and that the judge failed to consider the mother’s mitigating actions and shifted the burden of proof by relying on a statutory inference of neglect under D.C.Code § 16-2316(c) (1981). The government must prove by a preponderance of the evidence that a child is abused. See In re B.K., 429 A.2d 1331, 1333 (D.C.1981); see also In re J.S.R., 374 A.2d 860, at 864 (D.C.1977) (pre*1383ponderance standard is “a comparative one requiring the court to merely determine who has the most competent evidence”).1 All parties agree, as do we, that the judge must apply an objective standard in determining whether the parental action constitutes abuse. On that basis, the judge found that S.K. was an abused child because a reasonable person, knowing of S.K.’s severe mental problems, would have restrained his or her reaction in responding to an admittedly potentially life-threatening circumstance. We concur in all except Part IV and footnote 10 of Judge Schwelb’s opinion, concluding that the evidence on which the trial judge relied supports his findings.
Dr. Vernberg testified about S.K.’s mental condition and opined that the reaction of the mother and the stepfather in beating S.K. for starting the fire was inappropriate. The mother admitted that she was aware of S.K.’s severe mental problems and still had beaten her with a belt when S.K. denied her culpability and stared blankly into space. When S.K. was admitted to the psychiatric ward of Children’s Hospital several welts were visible on her body, and one was still visible a week and one-half later. Under these circumstances we hold that there was sufficient evidence for the judge to find that the corporal punishment of S.K. by the mother was excessive, and consequently, that S.K. was a neglected child as a result of abuse.
That the record also contains evidence that is, arguably, supportive of the mother’s viewpoint of what happened is not dispositive. The trial judge was in the best position to evaluate the mother’s and S.K.’s credibility. In finding abuse, the judge could properly emphasize the mother’s knowledge of S.K.’s severe mental problems in view of the assessment by hospital officials that the mother, although able to present herself well, lacked appropriate appreciation of the effect of her treatment of S.K. and was unwilling to acknowledge its consequence.
In addition, we disagree with appellants’ contention that the trial judge made four critical findings of fact that require reversal. First, they claim there was no evidence that the mother acted in a rage. Regardless of whether we agree with appellants that this was a critical finding, there was evidence from which the judge could make such a reasonable inference. Although the mother realized S.K. was acting inappropriately, she repeatedly beat her with a belt and admitted to Dr. Vernberg that she was afraid that she would not have been able to control herself if she had not stopped to seek assistance.
Appellants’ second contention, that there was no evidence the beatings resulted in abrasions, is meritless in view of evidence of welts on S.K.’s body, at least one of which was still visible when the police investigated on July 25, more than a week after the beatings. Their third contention, that there was no evidence to support the judge’s finding the mother, knowing of S.K.’s emotional problems, should have acted differently, also is meritless. Again, there was Dr. Vernberg’s testimony on which the judge was entitled to rely in applying an objective standard. Finally, appellants’ contention that there was no evidence that such physical discipline was likely to exacerbate S.K.’s condition ignores the expert testimony about the nature of S.K.’s mental condition, its causes, the inappropriateness of such behavior, and the effect of the beatings. Therefore, the evidence was sufficient to support the trial judge’s finding that beatings were likely to exacerbate S.K.’s fear of her mother and cause her to withdraw and to experience hallucinations and death wishes.
*1384Accordingly, declining to exercise our jurisdiction to decide the vagueness challenge, we affirm the judgment.2
. The judge needlessly relied upon D.C.Code § 16-2316(c), which creates a permissive inference of neglect based on mental or physical injuries of a child which are not satisfactorily explained. The circumstances surrounding S.K.’s injuries were not in question; the mother admitted that she and the stepfather were responsible for inflicting the July 13 welts and bruises. Cf. In re L.E.J., 465 A.2d 374 at 376-77 (D.C. 1983) (mother never provided consistent or credible account of how five-week-old son incurred fractures of both arms where medical testimony indicated such injuries were unusual in children of this age).
Contrary to appellants’ contention, the trial judge’s use of § 16-2316(c) did not shift the burden of proof. The judge noted specifically that the inference was not the same as a judgment based on a finding of neglect.
. Appellants contend that D.C.Code § 16-2301(9)(A) is unconstitutionally vague because the term "abused" is inadequately defined and that the use of an objective standard is inadequate to save the statute because there is no general consensus on when discipline of a child becomes abuse. See generally Taylor v. Montgomery, 413 A.2d 923, 925 (D.C.1980) (due process). Since appellants raise their constitutional challenge to the neglect statute for the first time on appeal, our review is entirely discretionary. In re W.E.P., 318 A.2d 286, 289 (D.C.1974); Foster v. United States, 290 A.2d 176, 177 (D.C.1972). Ordinarily, the court has declined to exercise its discretion, to consider constitutional challenges raised for the first time on appeal unless "the statute is so clearly unconstitutional that it should have been ruled upon by the trial court despite the failure of appellant to raise the point below....” In re W.E.P., 318 A.2d 286, at 289 (D.C.1974) (quoting Williams v. United States, 237 A.2d 539, 540 (D.C.1968)). We find no such circumstances nor any other reason compelling our review.
The statute prohibits excessive corporal punishment and the conduct on which the trial judge based his finding of abuse — repeatedly beating with a belt a psychologically disturbed eight-year old who is acting strangely — clearly falls within the express terms prescribed by the statute. Cf. District of Columbia v. B.J.R., 332 A.2d 58, 60 (D.C.), cert. denied, 421 U.S. 1016, 95 S.Ct. 2425, 44 L.Ed.2d 685 (1975) (D.C.Code § 16-2301(8) (1981)). See also In re B.K., supra, 429 A.2d at 1334 (D.C.Code § 16-2301(9)(B) & (C)); Robinson v. United States, 317 A.2d 508, 510 & n. 2 (D.C.1974) (assault with a dangerous weapon). Other jurisdictions have uniformly upheld that their child neglect and abuse statutes against a vagueness challenge even when the statutory language was more general than § 16-2301(9)(A) and (23).