(1) The trial court did not abuse its discretion by qualifying the State’s witness as an expert in the fields of forensic blood alcohol physiology and pharmacology, breath and blood alcohol testing, and the effects of drugs on human performance and behavior. The witness was the head of the Forensic Test for Alcohol branch of the N.C. Department of Health and Human Services, oversaw the training of law enforcement officers on the operation of alcohol breath test instruments and of drug recognition experts. His specialty is in "scientific issues related to breath testing and blood testing for drugs and alcohol." He has a B.A. and master's in biology and is certified as a chemical analyst. He attended courses on the effects of alcohol on the human body and various methods for determining alcohol concentrations and the effects of drugs on human psychomotor performance. He has published several works and has previously been qualified as an expert in forensic blood alcohol physiology and pharmacology, breath and blood alcohol testing, and the effects of drugs on human performance and behavior over 230 times in North Carolina. Despite his lack of a formal degree or certification in physiology and pharmacology, his extensive practical experience qualifies him to testify as an expert. (2) The trial court did not abuse its discretion by admitting the State’s expert’s testimony regarding the relative amount of cocaine in the defendant's system at the time of the collision and the effects of cocaine on an individual's ability to drive. The defendant argued that the testimony was based upon unreliable methods. Based on cocaine’s half-life and a report showing unmetabolized cocaine in the defendant’s system, the expert determined that the defendant had recently used cocaine and that the concentration of cocaine in his system would have been higher at the time of the crash. On cross-examination, he testified that there was no way to determine the quantity of cocaine in the defendant's system. He further testified as to the effects of cocaine on driving ability, noting a correlation between "high-risk driving, speeding, [and] sometimes fleeing . . . when cocaine is present." He based this testimony on a study which "looked at crashes and behaviors and found [an] association or correlation between the presence of cocaine and high-risk driving." He testified that it was possible for cocaine to be detected in a person's system even after the person was no longer impaired by the drug. The expert’s testimony that the level of cocaine in the defendant's system would have been higher at the time of the collision and his testimony as to the general effects of cocaine on a person's ability to drive was supported by reliable methods. Notably, the defendant's expert corroborated this testimony both as to the half-life of cocaine and the existence of studies showing a correlation between the effects of cocaine and "high-risk" driving.