*939|65 (concurring) — I concur with the majority opinion. I write separately to respond to the suggestion of my learned friend Justice Sanders that the majority “permits the admission of expert testimony concerning the credibility of a criminal defendant’s accuser.” Dissent at 940. I disagree.
Chambers, J.¶66 Neither the majority nor I condones an expert witness commenting on another witness’s credibility when credibility has not been made an issue at trial. Such testimony will all too often be prejudicial, especially when clothed in the uniform of a doctor or a police officer. See generally State v. Demery, 144 Wn.2d 753, 765, 30 P.3d 1278 (2001). But this question is not before us because the experts in these cases did not comment upon the children’s credibility.
¶67 Experts are permitted to testify on subjects that are not within the understanding of the average person. ER 702; see also State v. Petrich, 101 Wn.2d 566, 575-76, 683 P.2d 173 (1984) (finding no abuse of discretion in allowing expert to testify that sexually abused children often do not promptly report the abuse). We allow experts to express opinions concerning their fields of expertise when those opinions will assist the trier of fact. ER 702; cf. ER 701.
f 68 Often, it would be very helpful to the judge or jury to know whether a statement, condition, or alleged fact is consistent with the other evidence in the case or similar cases. E.g., State v. Florczak, 76 Wn. App. 55, 73, 882 P.2d 199 (1994). A properly offered expert opinion on whether a child’s demeanor during an investigatory interview was (or was not) consistent with what the expert would expect is not a comment on the child’s credibility.
|69 That a statement, condition, or alleged fact is consistent or inconsistent with the expert’s observations or opinions may be a comment on the reliability of the statement, condition, or alleged fact, but is not a comment on the credibility of the witness. The mere fact that one witness disagrees with another does not mean one witness is commenting on the credibility of the other. Neither is an expert’s opinion on whether (or not) the child’s physical *940condition was consistent with that of a child who had been sexually abused a comment on credibility. These are simply opinions based on knowledge outside the understanding of the average person that could “assist the trier of fact to understand the evidence.” ER 702.
f 70 It was not an abuse of discretion to admit the expert testimony. I concur.