Defendantr-Appellant Chakkira Wonnum appeals her Superior Court convictions of Murder First Degree, Possession of a Firearm During the Commission of a Felony, Assault First Degree, Robbery First Degree, Conspiracy Second Degree, and Possession of a Deadly Weapon by a Person Prohibited. Wonnum presents three arguments on appeal. First, she argues that the trial judge erroneously precluded expert testimony about her psychological disposition. Second, she contends that the trial judge erred by refusing to give a duress instruction. Finally, Wonnum argues that the trial judge violated her constitutional right to a trial by jury when the trial judge interjected her own recollection of a fact to the jury.
We hold the trial judge did abuse her discretion by precluding expert testimony on Wonnum’s psychological disposition. We also hold that the trial judge erred by refusing to give a duress instruction to the jury. By recounting her own recollection of Wonnum’s age to the jury, the trial judge also erred, but we find the error harmless.
Accordingly, we reverse Wonnum’s convictions and remand to Superior Court for further proceedings in accordance with this opinion.
FACTS
In February 2005, 17 year old Chakkira Wonnum ran away from home to live with her 23 year old boyfriend, Steve Martin. During the course of their relationship, Martin abused Wonnum, who frequently had noticeable bruises and black eyes.
On May 18, 2005, Martin gave Wonnum a loaded revolver, placed it in her purse, and told her to rob somebody because he needed money. She called a former boy-*571Mend, Johnnie Jackson, and asked him to meet her. Jackson was a drug dealer and Wonnum believed that he would have money. Around 9:00 p.m., Jackson called Annette Boyd and asked her to drive him to meet Wonnum. Boyd agreed. She placed her four-year old son in his car seat in the back of her vehicle and drove two blocks to pick up Jackson. Boyd then drove Jackson to Wilmington to meet Wonnum.
When Boyd and Jackson arrived, Won-num got into the rear passenger side of the vehicle, directly behind Jackson. Following a 15 minute stop at a house on 6th Street for drugs, the group headed back on 1-95 in the direction of Jackson’s house. As Boyd got off the Route 141 exit, Won-num drew the revolver, aimed it at the back of Jackson’s head and told him to give her his money. After a brief struggle, Wonnum shot Jackson four times in the back of his head and neck, causing fatal injuries. Wonnum also shot Boyd in the arm during the altercation. Wonnum fired all nine rounds in the gun’s magazine.
After the shooting, Wonnum told Boyd to drive back to Wilmington and directed her to pull into a back alley off Maryland Avenue. Boyd grabbed her son and fled on foot down Maryland Avenue. Boyd then flagged down an elderly couple, told them what happened, and used their phone to call 911. Boyd suffered permanent nerve damage to her arm as a result of her injuries.
Wonnum took Jackson’s money ($50.00) and cell phone from his pockets and fled in the opposite direction on Maryland Avenue. She called Martin’s house, and Martin’s mother, Joann Parrish, answered the phone. After Wonnum told Parrish that she had shot someone, Parrish told her to get rid of the gun. Wonnum disposed of the revolver in some bushes in front of a house on Maryland Avenue and then hitched a ride back to Martin’s house.
Martin directed Wonnum to change her clothes. They and Martin’s Mend “Bump” then fled to New Jersey, where Martin and Bump burned Wonnum’s blood-covered clothes. After several days, Wonnum returned to her mother’s house in Wilmington. Police arrested Wonnum, and the State indicted her on charges of intentional murder, felony murder, assault first degree, two counts of robbery first degree, conspiracy second degree, and related weapons offenses.
On June 20, 2006, the State moved in limine to exclude from evidence a psychological report on Wonnum and to bar the presentation of a duress defense. The trial judge granted the motion to exclude the expert report and reserved decision on the duress defense. On July 10, 2006, the State nolle prossed one count of robbery first degree and one count of possession of a deadly weapon by a person prohibited.
On July 11, 2006, Wonnum went to trial. At the prayer conference, the trial judge denied Wonnum’s request for a duress instruction. The jury hung on the charge of intentional murder and the accompanying weapons offense, but found Wonnum guilty of the remaining offenses. Post trial, Wonnum requested that the trial judge sentence her as guilty but mentally ill. The trial judge denied the motion, and on October 27, 2006, sentenced Wonnum to life plus seventeen years in prison.
DISCUSSION
I. Expert Testimony
Wonnum first argues that the Mai judge erred when she precluded expert testimony regarding her psychological state. On March 28, 2006, defense counsel sent a copy of a report from a 2005 psychological examination of Wonnum to the state prosecutors. The report contained an explanation of Wonnum’s his*572tory of abuse and an evaluation of Martin’s abusive relationship with her. It detailed sexual abuse at a very young age, and diagnosed Wonnum with bi-polar disorder, depression, and post-traumatic stress disorder. Anticipating that Won-num would attempt to admit the report at trial in support of a duress defense, the State moved in limine to exclude the evaluation. The State argued, in support of its motion, that the report was irrelevant because “Wonnum’s life of abuse and drugs does not make Johnnie Jackson’s killing or the shooting of Annette Boyd more or less probable ... [and] any probative value [the] report may bring is highly outweighed by the confusion it will create in the jury’s mind especially in the absence of an insanity defense.” During an office conference with the trial judge, defense counsel requested the opportunity to respond to the State’s motion in writing. Although the trial judge never read the report to which the State objected, she found the report irrelevant to a duress defense and granted the State’s motion. We review the exclusion of evidence for abuse of discretion.1
Duress is a recognized affirmative defense to criminal liability in situations where a third party coerces the defendant by threat of bodily harm to commit a crime.2 The defendant must establish duress by a preponderance of the evidence.3 Duress is defined in the Delaware Code as:
(a)In any prosecution for an offense, it is an affirmative defense that the defendant engaged in the conduct charged to constitute the offense because the defendant was coerced to do so by the use of, or a threat to use, force against the defendant’s person or the person of another, which a reasonable person in the defendant’s situation would have been unable to resist.
(b) The defense provided by subsection (a) of this section is unavailable if the defendant intentionally or recklessly placed himself or herself in a situation in which it was probable that the defendant would be subjected to duress.
(c) It is not a defense that a woman acted on the command of her husband, unless she acted under such coercion as would establish a defense under this section. The presumption that a woman acting in the presence of her husband is coerced is abolished.4
In evaluating a duress defense, a jury may consider the immediacy of the threat; the explicitness of the threat; the nature of the physical injury threatened; the time when the threat is to be carried out; the ability to escape from the coercer; and the coercer’s presence, or absence at the time of the commission of the crime.5 The rationale underlying duress as an affirmative defense is that “a man should not be held criminally responsible for a crime when commanded to do it under circumstances in which a reasonable person would have been unable to resist the compulsion to do it.”6 The trier of fact evaluates the factual circumstances relating to the force or threat of force objectively using a reasonable person standard.7 The statute re*573quires the defendant to prove by a preponderance of the evidence that a reasonable person would have been unable to resist the force or threat of force made.
We find that the trial judge erred by excluding the psychological report, both as a matter of process and substance. As the State conceded at oral argument, the trial judge never read the report before excluding it. She limited her consideration of the report to counsels’ oral representations at an office conference. A ruling on the admissibility of a report into evidence without an understanding of the report’s actual contents or detailed written proffers on its content, is an abuse of discretion.
In her ruling on the motion in limine, the trial judge remarked that “[Wonnum’s] psychological status or whatever background she’s has [sic] in terms of her family background or whatever hard life she’s had is totally and completely irrelevant in the guilt phase.” The trial judge’s conclusory assumption ignored the fact that the report contained more than a psychological diagnosis; it also contained an opinion on why Wonnum would legitimately perceive (or by inference any reasonable person similarly situated) Martin to be a threat. Expert testimony is relevant if it “will assist the trier of fact to understand the evidence or to determine a fact in issue[.]”8 Consistent with the second section of the duress statute, § 431(b), the report offered a relevant explanation that Wonnum did not “intentionally or recklessly place ... herself’ in the situation, and addressed why Wonnum did not believe she could just simply ignore Martin’s demand. Therefore the trial judge should not have excluded the report solely because of a conclusory determination that “[Wonnum’s] psychological status or ... background” had no relevance to a duress defense.
11. Duress Jury Instruction
Wonnum next contends that the trial judge improperly denied her request for a duress instruction. The trial judge found that Wonnum failed to demonstrate that Martin had actually threatened her and thus would not give her requested duress instruction. We review the Superi- or Court’s denial of a requested instruction de novo.9
To establish the affirmative defense of duress, the defendant must show by a preponderance of the evidence that she was coerced to engage in the conduct charged by the use of, or a threat to use, force against her person or the person of another.10 Under 11 Del C. § 304(b), “Unless the court determines that no reasonable juror could find an affirmative defense established by a preponderance of the evidence presented by the defendant, the defendant is entitled to a jury instruction that the jury must acquit the defendant if they find the affirmative defense established by a preponderance of the evidence.” The affirmative defense is established by a preponderance of the evidence only if it is more likely than not that each element of the defense existed at the required time.11
In addition, for a duress instruction to be given, the trial judge must be “satisfied that some credible evidence supporting the defense has been presented.”12 Credible can be defined as capable of be*574ing believed. In Gutierrez v. State, in discussing the affirmative defense of self-defense, we held that the judge, in her role as gatekeeper, ensures “(1) that the affirmative defense evidence describes a situation that is within the realm of possibility, and (2) that such situation would legally satisfy the requirements of [the asserted affirmative defense.]”13 We went on in Gutierrez to cite with approval the proposition that, “If there is credible evidence supporting an affirmative defense, the court must instruct the jury on the defense even if the supporting evidence consists of highly improbable testimony by the defendant.” 14 Thus, as in Gutierrez, when the defendant presents some evidence capable of being believed, on each of the elements of an affirmative defense, whether the defendant has proved the affirmative defense by a preponderance of the evidence is a jury question.
We believe that the defendant’s testimony supported a jury instruction for duress. The defendant’s testimony is for the jury to believe or reject. Wonnum’s testimony, as well as the excluded psychological report, provides some credible evidence to support a duress instruction. As the Fifth Circuit wrote in United States v. Willis, “In determining whether the elements of duress are met, the fact-finder may take into account the objective situation in which the defendant was allegedly subjected to duress. In addition to the immediate circumstances of the crime, this would include evidence concerning the defendant’s past history with the person making the unlawful threat.”15 Wonnum testified that when she disobeyed Martin, he would curse, yell, and hit her. On an earlier occasion, when he wanted her to commit a robbery and she would not, he beat her. On May 18, 2005, Martin told her to “rob someone,” he put the loaded gun in her purse, and directed her to call someone. Wonnum testified at trial she “wanted to get [the robbery] done so Martin can leave me alone.” She also testified that she was afraid Martin or one of his friends would hurt her family if she did not follow his orders.
The trial judge’s factual findings prevented Wonnum from presenting a viable duress defense. After finding that Martin made no specific or immediate threat to Wonnum, that he was absent at the time of the shootings, and that Wonnum had the opportunity to “escape” and after excluding the expert report without having read it or considered any of its implications, barring a duress defense and refusing to instruct the jury accordingly, became a self-fulfilling prophecy. While the record superficially supports those findings (depending on one’s view of how specific the threat must be), a “threat” can also mean an implied threat the genuineness of which can be reinforced by earlier conduct. Wonnum’s testimony supported, by actual relationship history, an implied, current threat. Based on Wonnum’s testimony, it was within the realm of possibility that Wonnum was acting under duress when she committed the crime of robbery. The *575jury, not the trial judge, should have decided whether Wonnum satisfied her burden of proof to establish that defense by a preponderance of the evidence.
We note that our colleague dissents from this, Part II, of the Opinion. We do not hesitate to point out that in his thoughtful and articulate dissent, he agrees with much of our analysis in Part II though he parts from us by concluding that the trial judge rightfully made a unilateral judgment that a reasonable person would have “found several legal alternatives” to both robbing and killing Jackson and that, therefore, the trial judge correctly found in the first instance as a matter of law, that a reasonable person in Wonnum’s situation would have been able to resist Martin’s coercive conduct.
We disagree. We do so because evidence both admitted — Wonnum’s testimony — and improperly barred — the psychological report — offered “some credible evidence supporting” the duress defense. As we point out in Part III, under the Delaware Constitution, juries, not judges, are fact finders in Delaware jury trials.16
Superficially, characterizing the duress defense as “battered woman syndrome” and rejecting it, without even reading or considering the psychological report does not morph the trial judge’s rejection of the request for a jury instruction on duress into a ruling as a matter of law. Here, the jury should have weighed Wonnum’s ability to pursue legal alternatives and assessed her credibility, that of the report and the application of those facts and opinion if believed, to both elements of the duress defense. It should have been they, and not the trial judge, who answered the questions of whether a reasonable person in Wonnum’s situation would have been able to find legal alternatives to robbing and shooting the victim.
Accordingly, we hold that the trial judge committed reversible error when she failed to instruct the jury on the duress defense.
III. Trial Judge’s Statement to the Jury
Finally, Wonnum argues that the trial judge violated the Delaware Constitution when the trial judge related her own recollection of Wonnum’s age to the jury. During deliberations, the jury requested a definition of the term “juvenile.” The trial judge properly defined the term as meaning “an individual under the age of 18 years.” After giving this definition, however, the trial judge added “[i]n this case the defendant, I think, indicated that she was 17 at the time that this occurred.” *576Because Wonnum failed to object to this statement at trial, we review for plain error.17 “Plain error exists when the error was ‘so clearly prejudicial to [a defendant’s] substantial rights as to jeopardize the very fairness and integrity of the trial process.’ ”18
Under the Delaware Constitution, “[j]udges shall not charge juries with respect to matters of fact, but may state the questions of fact in issue and declare the law.”19 Although the trial judge improperly commented on Wonnum’s testimony, the comment was harmless error.20 Won-num’s age was relevant only to the charge of possession of a deadly weapon by a person prohibited.21 More importantly, her age was never in dispute at trial. Wonnum herself and other witnesses testified that she was 17 and defense counsel referred to Wonnum as a “17 year old” several times during closing arguments. Thus, any error resulting from the comment was inconsequential at best.
CONCLUSION
For the foregoing reasons, we REVERSE and REMAND to the Superior Court for a new trial.
. Capano v. State, 781 A.2d 556, 586 (Del.2001).
. Feliciano v. State, 332 A.2d 148, 149 (Del.1975).
. 11 Del. C. § 304(a); Foraker v. State, 394 A.2d 208, 214 (Del.1978).
.11 Dei. C. § 431.
. 11 Del. C. Ann. § 431.
. Delaware Criminal Code Commentary § 431, at 94 (1973).
. Id.
. D.R.E. 702.
. Smith v. State, 913 A.2d 1197, 1210 (Del.2006).
.11 Del. C. § 304(a); 11 Del. C. § 431.
. 11 Del. C. § 304(c).
. 11 Del. C. § 303(a).
. 842 A.2d 650, 653 (Del.2004).
. Id. (citing People v. Garcia, 1 P.3d 214, 221 (Colo.Ct.App.1999)); see. also Commonwealth of Pennsylvania v. DeMarco, 570 Pa. 263, 809 A.2d 256, 262 (2002) (holding that once evidence is presented in support of the duress defense, the trial judge must give the jury instruction).
. 38 F.3d 170 n. 8 (5th Cir.1994) (citing United States v. Webb, 747 F.2d 278, 285 (5th Cir.1984)); see also United States v. Bell, 855 F.Supp. 239, 241 (N.D.Ill.1994) ("A defendant’s state of mind as it relates to whether her fear was reasonable is an objective criterion which may be testified to by defendant and considered by the trier of fact in this regard.”).
. The right to trial by jury in the 1776 Delaware Declaration of Rights and Fundamental Rules of the Delaware State, which was preserved by the “heretofore” text in the 1792 Constitution, referred to the right to trial by jury regarding factual issues as a great security of "the lives, liberties, and estates of the people.” Similarly, in a letter to Pierre S. DuPont, Thomas Jefferson described the fact-finding function of jurors as:
|T]he very essence of a Republic.... We of the United States ... think experience has proved it safer for the mass of individuals composing the society to reserve to themselves personally the exercise of all rightful powers to which they are competent.... Hence, with us, the people ... being competent to judge of the facts occurring in ordinary life, ... have retained the functions of judges of facts under the name of jurors....
I believe ... that action by the citizens, in person in affairs within their reach and competence, and in all others by representatives chosen immediately and removable by themselves, constitutes the essence of a Republic.
Randy J. Holland, The Delaware Constitution: A Reference Guide 149-50 (quoting Letter from Thomas Jefferson to Pierre S. DuPont (Apr. 4, 1816), in 4 Annals of America 414 (Encyclopedia Britannica 1976) (emphasis added)).
. Bullock v. State, 775 A.2d 1043, 1046 (Del.2001).
. Id.
. Del. Const, art. IV, § 19.
. See Van Arsdall v. State, 524 A.2d 3, 10-11 (Del.1987) (adopting the U.S. Supreme Court harmless error analysis approach for analyzing harmless error under the Delaware Constitution).
. 11 Del. C. § 1448(a)(5) (prohibiting juveniles from possessing handguns).