The state has petitioned for review of our decision that affirmed without opinion the trial court’s order excluding from evidence the results of a Horizontal Gaze Nystagmus (HGN) test. State v. O’Key, 115 Or App 102, 835 P2d 964 (1992). We treat the petition as one for reconsideration, ORAP 9.15(1), and allow it.
Defendant was charged with driving under the influence of intoxicants. ORS 813.010. Before trial, he moved to exclude evidence of his performance of the HGN test. The state intended to offer the evidence at trial to prove that he was under the influence of intoxicants and/or that his blood alcohol level was greater than .08 percent. The trial court granted the motion, ruling that “the probative value of the evidence of the HGN test is outweighed by the danger of unfair prejudice because of the potential for error and subjectivity of [the test.]” The state appeals pursuant to ORS 138.060(3).
The state describes the HGN test as a procedure
“in which a police officer requests a Driving Under the Influence of Intoxicants suspect to follow a fixed point, such as the tip of a pen, with his eyes while keeping his head still. The officer moves the point slowly from a position in front of the subject to the side, looking for three things: Whether there is oscillation (nystagmus) of the eyeball at an angle of 40 degrees; whether the eye follows the motion smoothly or jerkily; and whether there is nystagmus at maximum deviation (when the eye is looking fully to the side). The test is repeated on the subject’s other side, resulting in a six-part test. The presence of nystagmus or ‘eyeball bounce’ in four or more parts of the test indicates that the subject is impaired by alcohol.”
The trial court evaluated extensive scientific testimony and evidence concerning the test, weighed the factors enunciated by the Supreme Court in State v. Brown, 297 Or 404, 687 P2d 751 (1984), and arrived at its conclusion under OEC 403.1 Under Brown, expert testimony must be relevant *57under OEC 4012 and provide assistance to the trier of fact under OEC 702.3 If the requirements of OEC 401 and OEC 702 are met, then the testimony is subject to exclusion only if it falls within the provisions of OEC 403. Regarding the standard of review that is applicable, the court in Brown said:
“Oregon Evidence Code Rule 403 codifies the common-law discretionary power of the trial judge in balancing probative value of evidence against its prejudicial effect. But, this so-called ‘balancing’ rule does not always call for the exercise of discretion by the trial court. Notwithstanding the usual deference to trial court discretion, we as an appellate court retain our role to determine the admissibility of scientific evidence under the Oregon Evidence Code.” 297 Or at 442.
See also 297 Or at 417 n 4.
The state argues that the HGN test is based on scientifically valid principles and, when administered properly, accurately indicates whether a driver is impaired by alcohol. According to the state, the test is the most accurate of all of the approved standardized field sobriety tests that indicate alcohol impairment. It also contends that if the nystagmus is present at an angle of 40 degrees at maximum deviation in both eyes, then the test accurately shows that the blood alcohol concentration will be .10 percent or greater. It follows, according to the argument, that evidence of the HGN test results is admissible to establish that defendant’s blood alcohol concentration was over the legal limit fixed by ORS 813.010(l)(a), as well as being probative of the standard prescribed by ORS 813.010(l)(b).4
*58In Brown, the court said that the following factors are to be considered as guidelines for reaching a decision about the probative value of evidence under OEC 401 and OEC 702:
“(1) The technique’s general acceptance in the field;
“(2) The expert’s qualifications and stature;
“(3) The use which has been made for the technique;
“(4) The potential rate of error;
“(5) The existence of specialized literature;
“(6) The novelty of the invention; and
“ (7) The extent to which the technique relies on the subjective interpretation of the expert.” 297 Or at 417.
Those factors are not exclusive, but an analysis of each factor is necessary.
Regardingthe general acceptance of the HGN test as an indicator of whether a driver is impaired, the Department of State Police has determined that the HGN test qualifies as a “field sobriety test” within the meaning of ORS 801.272, in that it “enables a police officer or trier of fact to screen for or detect probable impairment from intoxicating liquor.” See OAR 257-25-020(1); State v. Scott, 121 Or App 308, 854 P2d 991 (1993). Furthermore, defendant concedes that, “in combination with other officer observations, the test is a reliable, if an imprecise indicator of the probability of impairment.” Also, defendant does not dispute the trial court’s finding that all of the experts who testified about the reliability of the test as an indicator of alcohol consumption were qualified. However, defendant attacks the ability of arresting officers to determine whether or not the phenomena occurs. As part of the procedure, the officer establishes a mid-point directly from the person by using the individual’s nose or eyeball as a fulcrum for moving the pen in an arc to each side. Officers are *59trained to move the pen slowly to avoid creating jerking motions of the eye. The officer brings the pen to a 40-degree point and notes whether nystagmus is present at that angle. In this case, the arresting officer had performed the test on approximately 300 drivers and had undergone a 16-hour training period in which he had to accurately identify subjects who had consumed alcoholic beverages.
Regarding the use that has been made of the technique, the state offered evidence that the HGN test is used primarily as a field sobriety test for alcohol impairment and is less commonly used to determine a specific blood alcohol level. It is used in combination with other field sobriety tests to make a probable cause determination as to whether the person is under the influence. As to the potential rate of error, testimony shows that, when used correctly by a qualified officer and when employed along with other field sobriety tests, a nystagmus that is present at 40 degrees indicates a blood alcohol level of over .10 percent, with an accuracy of 80 percent. However, defendant disputes the accuracy of the test results, because numerous other possible factors could cause nystagmus. Testimony shows that about three percent of the population suffers from non-alcohol caused nystagmus and that, within that group, there are 50 to 100 causes of the phenomenon. Non-alcohol induced nystagmus typically is asymmetrical and officers are trained to look for that aspect. The state also points out that persons suffering from known causes of non-alcohol induced nystagmus, such as people with brain tumors, multiple sclerosis, brain damage or stroke victims are less likely to be encountered driving a car. Part of the training that officers undergo requires them to ask before administering the test whether the person has a head injury, is ill or is taking medication.
Defendant concedes that there is substantial specialized literature about the HGN phenomenon, and that the testing for it and the use of the test in combination with other field sobriety tests is no longer “novel.” Finally, the state argues that the presence or absence of nystagmus is no more subjective than the observation of other indicia of intoxication such as swaying, staggering, bloodshot eyes or slurred speech. The officer must make three observations: Do the eyes jerk or do they move smoothly from mid-point to *60end-point; is there continuing jerking or bouncing when the eyes are held at the end-point; and do the eyes display jerking at a fixed angle of 40 degrees.
Defendant argues that, when the factors listed in State v. Brown, supra, are used to evaluate the HGN test results in this case, the results are not admissible. He points to the evidence that nystagmus varies depending on the individual, that in order to accurately measure the 40 percent angle, a protractor device necessarily is required to be used, and that if the officer moves the pen too rapidly or if it is slightly above the “smooth pursuit line,” the results are inaccurate. He also relies on evidence that the results are inaccurate as to those who suffer from acute myopia and that the cumulative effect of alcohol, medication and fatigue can influence eye movement.
Whether evidence is relevant under OEC 401 or helpful under OEC 702 depends on the purpose for which it is being offered. Based on the foregoing, there is no question that evidence of the results of defendant’s HGN test make the existence of the fact that he was under the influence of alcoholic beverages more likely and would assist the trier of fact in making that determination. Also, a nystagmus could corroborate a chemical analysis of the blood or breath and assist the trier of fact in the evaluation of the accuracy of an intoxilyzer or blood analysis result.5
The trial court concluded that the probative value of the evidence was outweighed by the danger of unfair prejudice, OEC 403, and gave as its reasons the potential for error and the subjectivity of the test. As we have noted, the HGN test result is relevant evidence under OEC 401 and helpful to the trier of fact under OEC 702. OEC 403 requires us to evaluate the degree to which the trier of fact may be overly impacted or prejudiced by a purported implication of reliability or validity of the evidence and whether admission of the test result will cause the trier of fact to abrogate its role to evaluate all of the facts. We do not think that HGN test results have that kind of impact. As with testimony about all *61field sobriety tests, the evidence about how the test was performed and defendant’s responses to it is subject to cross-examination.
The dissent’s concern is that errors may occur because the test is administered in the field when there is no way to insure the accuracy of the angle used to measure the nystagmus. Other field sobriety tests require the officer to demonstrate physical movements or patterns of speech and require the driver to perform them under the officer’s directions. Because the manner of administration is subject to cross- examination, those test results are not excluded. Any deficiencies go to the weight to be given to the evidence. A similar analysis applies here. The HGN test result is one of many field sobriety test results that may be admitted into evidence during a trial, and it is for the trier of fact to determine whether the officer used the proper angle. We conclude that the evidence is not so prejudicial that its probative value is outweighed. The trial court erred when it excluded from evidence the observations of the officer as to defendant’s reactions to the HGN test and the officer’s testimony about what the results meant to him.
Reconsideration allowed; decision vacated; reversed and remanded.
OEC 403 provides:
“Although relevant, evidence may be excluded if its probative value is substantially outweighed by the danger of unfair prejudice, confusion of the *57issues, or misleading the jury, or by considerations of undue delay or needless presentation of cumulative evidence.”
OEC 401 provides:
“ ‘Relevant evidence’ means evidence having any tendency to make the existence of any fact that is of consequence to the determination of the action more probable or less probable than it would be without the evidence.”
OEC 702 provides:
“If scientific, technical or other specialized knowledge will assist the trier of fact to understand the evidence or to determine a fact in issue, a witness qualified as an expert by knowledge, skill, experience, training or education may testify thereto in the form of an opinion or otherwise.”
ORS 813.010(1) provides:
“A person commits the offense of driving while under the influence of intoxicants if the person drives a vehicle while the person:
*58“(a) Has .08 percent or more by weight of alcohol in the blood of the person as shown by chemical analysis of the breath or blood of the person made under ORS 813.100, 813.140 or 813.150;
“(b) Is under the influence of intoxicating liquor or a controlled substance; or
“(c) Is under the influence of intoxicating liquor and a controlled substance.”
Proof of nystagmus could corroborate a chemical analysis of defendant’s breath or blood that shows that a defendant has .08 percent or more by weight of alcohol in his blood, just as other forms of physical impairment are corroborative, but is not prima facie evidence of alcohol content.