Appeal from the Circuit Court of Winnebago County. No. 99--MR--244 Honorable Joseph G. McGraw, Judge, Presiding.
 The opinion of the court was delivered by: Justice Callum
 Respondent, Shawn Lourash, appeals a judgment finding that he is a sexually violent person and ordering him committed to a Department of Human Services (DHS) treatment facility for six months or until further order of the court. On appeal, respondent argues that the trial court erred in denying his motion for a Frye hearing (see Frye v. United States, 293 F. 1013 (D.C. Cir. 1923)) on the admissibility of scientific evidence that the State's expert witnesses used in forming their opinions. We hold that although the trial court erred in denying respondent a Frye hearing, the error was harmless. Therefore, we affirm.
 On December 14, 1999, the State filed a petition under the Sexually Violent Persons Commitment Act (Act) (725 ILCS 207/1 et seq. (West 1998)), alleging the following facts. On January 28, 1991, respondent was adjudicated delinquent, based on his commission of aggravated criminal sexual assault, and placed in the youth division of the Department of Corrections (DOC). On September 19, 1998, in case No. 96--CF--2793, respondent was sentenced to six years in the DOC for an adult conviction of predatory criminal sexual assault. *fn1 He was scheduled to start mandatory supervised release (parole) on December 17, 1999. Dr. Agnes Jonas had diagnosed respondent with several mental disorders, including "Pedophilia, Sexually Attracted to Males and Females, Exclusive Type" and dysthymic disorder, not otherwise specified (NOS). Respondent was dangerous to others because his mental disorders made it substantially probable that he would engage in sexual violence again.
 The petition continued as follows. In the juvenile case, respondent committed two offenses against neighborhood children. He inserted his penis into the anus of a five-year-old boy and rubbed the vagina of a two-year-old girl against his groin. In September 1996, nine months after he was released from prison, respondent committed the offense in case No. 93--CF--2793 by inserting his finger into the vagina and anus of his eight-year-old niece. Respondent admitted that he also placed his penis into her mouth, vagina, and anus. Respondent had been receiving mental health services since he was age four, when he set his mother's bed on fire. He was hospitalized for psychiatric problems in March 1990 and August 1990, the second time after committing the sexual offenses in the juvenile case. In October 1990, respondent was hospitalized after being found unfit to stand trial. Respondent admitted to having sexually deviant fantasies involving children and to becoming sexually aroused upon seeing children on television.
 The petition attached Dr. Jonas's report, which was later admitted at trial. In the report, Dr. Jonas summarized the results of her evaluation, which was based on an interview with respondent and a review of his prison "master file" and medical files. Dr. Jonas stated that respondent, who was born June 4, 1976, had experienced an extremely unstable childhood. His parents divorced when he was three. At age four, respondent lit his mother's bed on fire and said that he wanted both of them to die. In 1990, he assaulted his mother in court. Respondent's parents fought over custody of him, and he regularly moved and changed schools. He was physically abused repeatedly and, at age 13, was sexually abused by a neighbor. Although respondent and his mother had acted violently toward one another, he felt extremely attached to her.
 Dr. Jonas's report also summarized the investigative reports pertaining to the acts that led to the 1991 juvenile adjudication and the 1998 conviction. Dr. Jonas concluded that respondent "is mostly in denial or at the very best inconsistent" in taking responsibility for his acts. He told Dr. Jonas that once or twice a week, he had sexual dreams about children. It was only after having these dreams that respondent took his medicine. If respondent saw a television show with small children, he became sexually aroused and turned off the set. When respondent was in prison in 1998, he violated regulations by engaging a cell mate in mutual masturbation at least 3 times in 30 days.
 Dr. Jonas noted that respondent was committed to the juvenile division of the DOC on January 28, 1991, was paroled "sometime in 1993," and "returned" as a parole violator about eight months later after he went "AWOL" and failed to attend outpatient therapy. (Respondent told Dr. Jonas that he had attended therapy regularly.) Respondent was again paroled "around 10/20/94" and discharged from parole on January 2, 1996, but he reoffended in September 1996.
 Dr. Jonas stated that at age four, respondent was diagnosed as "manic-depressive, schizophrenic, and ADHD" and placed on Ritalin. He had since been prescribed Tegretol, Tofranil, and Dexedrine. Tests performed in 1990 placed respondent's intelligence in the "low average" range. In October 1998, respondent was diagnosed with alcohol dependence and a history of major depressive disorder and placed on Sinequan. Later, he was taken off Sinequan and placed on Zoloft. Respondent told Dr. Jonas that he was not taking his Zoloft regularly but did so only after becoming sexually aroused by his fantasies or television.
 While incarcerated in 1998, respondent apparently expressed some interest in sex-offender therapy. However, he did not participate in any such treatment after September 1998, when he was transferred from Danville to Joliet after receiving a "sexual misconduct ticket." Since October 20, 1998, when he was transferred to the Dixon Correctional Center, respondent had not participated in any therapy even though it was available to "all inmates with sexual offenses."
 Dr. Jonas's report explained her diagnoses. Respondent met the criteria for pedophilia because of his recurring and intense sexual fantasies, urges, or behaviors involving prepubescent children; his desires as early as age nine "to have sex with children"; the three sexual offenses of which he had been found guilty; two other documented cases, which involved victims aged three and five; and his ongoing sexual fantasies about children. Respondent "admit[ted] that he will have to keep busy, day and night, to avoid sexually abusing and assaulting children once on parole." Respondent had dysthymic disorder in that he was chronically depressed. He suffered from personality disorder in that he failed to conform to social norms, tried to deceive others, manipulated children into sexual activity, acted aggressively on impulse, and lacked remorse for his antisocial behavior.
 Dr. Jonas's report concluded to a reasonable degree of psychological certainty that it was substantially probable that respondent would commit another act of sexual violence. She based her conclusion in part on the mental disorders she had diagnosed. Additionally, respondent had several characteristics that the 1996 Hanson-Bussiere "meta-analysis" found are associated with a high risk of recidivism. These included prior sexual offenses; sexually deviant fantasies; incomplete and limited treatment; a negative relationship with his mother; the fact that most of his victims were not family members; the fact that at least one victim was male; respondent's age (under 25); the early onset of his offenses; and respondent's never having been married. Furthermore, Dr. Jonas noted that respondent's score on the Minnesota Sex Offender Screening Tool-Revised (MnSOST-R), an actuarial instrument, placed him at "high risk" of reoffending.
 The case proceeded to a probable cause hearing. Dr. Jonas testified consistently with her report. She also testified that when she interviewed respondent, he denied that he had committed the juvenile offenses. Jonas noted that according to social history and clinical reports, respondent frequently refuses to talk about these subjects, sometimes feigning unconsciousness. Dr. Jonas had learned that after respondent was paroled from the DOC's youth division, he was supposed to have outpatient sex-offender treatment but violated his parole by failing to attend treatment regularly. Later, when he was incarcerated in the adult facility in Dixon, respondent was never in any therapy.
 After the trial court found probable cause and ordered respondent committed to the custody of the DHS, the matter went to trial. The parties stipulated to the admission of Dr. Jonas's report and her testimony at the probable cause hearing. The State then called Dr. Barry Leavitt, a licensed clinical psychologist and an expert in the evaluation and treatment of sex offenders. Dr. Leavitt testified as follows. After the probable cause finding, Leavitt was assigned to evaluate respondent in order to determine whether respondent had mental disorders that predisposed him toward future sexual violence and whether there was a substantial probability that respondent would again commit a sexually violent offense. Leavitt tested respondent and reviewed respondent's DOC files, treatment records, psychological evaluations, and police or investigative reports. Leavitt prepared a report in January 2000 and updates in April 2001 and March 2002. These reports were admitted into evidence.
 Initially, Leavitt had diagnosed respondent with "pedophilia, sexually attracted to both male and female children, non-exclusive type"; depressive disorder, NOS; and personality disorder, NOS, with antisocial features. After reviewing more comprehensive tests taken at "the treatment protection detention ...