FLETCHER, Circuit Judge:
Levolor Lorentzen, Inc. (“Levolor”) appeals from an adverse judgment in favor of plaintiff-appellee Ada Kern. Kern obtained a general verdict against Levolor on claims of wrongful termination, breach of the implied covenant of good faith and fair dealing, and age discrimination. Kern’s claims all arise under California law; jurisdiction is based on diversity. Levolor argues several grounds for reversal: (1) the district court’s refusal to grant it judgment notwithstanding the verdict; (2) the district court’s failure to order a new trial on the ground that the verdict and damages were against the manifest weight of the evidence; (3) judicial misconduct; (4) eviden-tiary error; and (5) error in the jury instructions. We find none of Levolor’s arguments meritorious and affirm the judgment of the district court.
FACTS
Kern was employed by Levolor to make wands for window blinds. [R.T. 7/27 at 37]. She began her employment in 1979, and was discharged on February 4, 1985, when she was 59 years old. [R.T. 7/27 at 37, 40]. Levolor employed three wandmak-ers, one on each shift. [R.T. 7/28 at 35]. Kern worked the third shift. [R.T. 7/27 at 37]. All three wandmakers were over 40 years old. [R.T. 7/29 at 50]. All had received the highest possible employee rating at Levolor (“AAA”). [R.T. 7/28 at 39; S.E.R. 1]. Of the three, Kern had the least seniority. [R.T. 7/28 at 45].
In late 1984 or early 1985, because of a slowdown in orders for window blinds, Le-volor decided to reduce its work force. [R.T. 7/28 at 39]. Management held meetings with employees to discuss the possibility of layoffs. [R.T. 7/28 at 41], Levolor intended to meet with all employees who might be subject to this layoff. [Id. at 42]. However, Kern was never informed about these meetings or about the possibility of layoff. [R.T. 7/27 at 97],
Employees were rated with a “golf score” to determine who would be laid off. [R.T. 7/28 at 41]. This score was based on employee rating, production and attendance. [S.E.R. 55-66]. The employees with the highest scores in each department were to be laid off first. [S.E.R. 55; R.T. 7/28 at 45-46]. Kern was not rated. [R.T. 7/28 at 45]. Levolor contends that Kern was not given a golf score because she was the only member of her department on the third shift. [Id.] However, Levolor did rate other employees who were the only people in their department. At trial, Levo-lor could not explain this disparity in treatment. [Id. at 103-04]. Although Levolor purported to compare golf scores only within departments, [Id. at 47-48], it did transfer two people between job classifications during the layoff. [Id. at 48].
Levolor had an express, written policy of laying off AAA-rated employees last. [S.E.R. 32]. Three other AAA-rated employees besides Kern were laid off in February. [S.E.R. 70], These three employees all were laid off voluntarily [Id.]; Kern, by contrast, was not given the opportunity to take voluntary layoff. [R.T. 7/27 at 97]. Although Kern had the least seniority of the three wandmakers, Levolor’s own Employee Handbook stated that seniority would not be a determinative factor in layoff decisions. [S.E.R. 32]. In addition, trial exhibits indicated that layoff decisions, in fact, were made solely on the basis of the employee’s grade (“AAA”, “AA”, etc.), production, and attendance. [S.E.R. 55-66].
On February 4, 1985, Levolor laid off several employees, including Kern. [S.E.R. 70]. As Levolor’s orders again increased, it began recalling the workers. [R.T. 7/28 at 53-54]. By May 3, 1985, the plant was again operating at essentially the same capacity as before the layoffs. [R.T. 7/29 at 70]. During the summer, Levolor hired [775]*775several temporary employees to perform odd jobs, including wandmaking on third shift. [R.T. 7/28 at 59]. Levolor also advertised for unskilled workers. [S.E.R. 74-75]. However, although most or all of the other employees laid off in February were recalled by June 5, 1985, Kern was not. [R.T. 7/29 at 70; 7/28 at 110]. Before her layoff, Kern had been given a positive rating for “adaptability”, [R.T. 7/27 at 59-60], and had performed various tasks besides wandmaking on an as-needed basis. [Id. at 65]. Nevertheless, Levolor did not offer to recall Kern to work in some position other than wandmaker.
In June 1985, Kern received a letter from the Levolor profit-sharing office notifying her that she had been “terminated” as of February 4, 1985. [S.E.R. 72]. She telephoned Levolor to determine her status, and was told she was on layoff. [R.T. 7/27 at 114]. However, the plant manager never responded to her written inquiry about her job status. [Id. at 114-15].
Meanwhile, Kern looked for work but was unable to find any. [R.T. 6/30 at 28]. She stopped her job search when she developed a skin rash and a nervous problem. [R.T. 7/27 at 113]. In September, 1985, she moved with her husband to Ohio to live with their children. [R.T. 7/27 at 29]. On October 18, 1985, Levolor sent Kern a brief letter stating that they had a job opening to discuss with her. [S.E.R. at 79]. By this time, Kern had already filed a complaint with the EEOC. [R.T. 7/27 at 115]. Levolor admitted that it intended to employ Kern in cutting an entirely new piece, called a “vogue valance”, in addition to performing her old job as wandmaker. [R.T. 7/28 at 54],
Levolor asserted that Kern was chosen for layoff because she had the least seniority and lowest production among the three wandmakers, and that the layoff was consistent with Levolor's contractual obligations to Kern. Kern asserted that Levo-lor had a contractual obligation to lay off AAA-rated employees last, that it failed to follow its own procedures in marking her for layoff, and that she was the victim of age discrimination.
The case was tried to a jury which found in favor of Kern and assessed damages of $237,000. The district court ordered a re-mittitur and entered judgment for Kern in the amount of $137,000. The district court declined to award attorney’s fees. [R.T. 10/01 at 5]. The district court had jurisdiction under 28 U.S.C. § 1332 (diversity); we have jurisdiction under 28 U.S.C. § 1291. The Notice of Appeal was timely filed. This case primarily requires us to determine whether the evidence is sufficient to support the jury’s verdict. Our review is narrow and limited.
I.
JUDGMENT NOTWITHSTANDING THE VERDICT
Jury verdicts are due considerable deference. In reviewing the district court’s denial of JNOV, we apply the same standard as the district court. We may reverse the district court only if we find that the evidence and its inferences, considered as a whole and viewed in the light most favorable to the nonmoving party, can support only one reasonable conclusion — that the moving party is entitled to judgment notwithstanding the adverse verdict. The verdict must be affirmed if supported by substantial evidence. William Inglis & Sons Baking Co. v. ITT Continental Baking Co., 668 F.2d 1014, 1026 (9th Cir.1982).
A. Wrongful Termination
Levolor contends that Kern failed to produce evidence that it breached an implied-in-fact employment contract. This argument has two parts: first, Levolor argues there was no contract, i.e., that Kern could be discharged at will; second, Levolor argues that even if there was a contract, it was not breached.
1. Existence of a Contract
California provides by statute that “[a]n employment, having no specified term, may be terminated at the will of either party on notice to the other.” Cal. Labor Code § 2922. Nevertheless, judicial decisions by California courts have estab[776]*776lished beyond cavil that an employer’s course of conduct can create implied-in-fact contractual terms of employment, including a covenant not to discharge an employee except for good cause or to discharge an employee only under certain conditions. See Pugh v. See’s Candies, Inc., 116 Cal. App.3d 311, 171 Cal.Rptr. 917 (1981); Foley v. Interactive Data Corp., 47 Cal.3d 654, 254 Cal.Rptr. 211, 222, 765 P.2d 373, 383-84 (1988). The existence of such implied promises is a question of fact for the jury to decide. Foley, 254 Cal.Rptr. at 223, 765 P.2d at 384-85. In determining whether such promises exist, the jury must look to the entire relationship of the parties. Id. at 224, 765 P.2d at 385. Factors include, but are not limited to, the terms of the employment manual, the employer’s personnel policies or practices, the longevity of plaintiff’s service, acts or communications by the employer reflecting assurances of continued employment, and whether plaintiff has received consistent promotions or salary increases. Id. at 225, 765 P.2d at 386.1
Although the evidence of an employment contract was not overwhelming, it was adequate to allow the issue to go to the jury. There was evidence that Levolor had a policy of laying off “AAA” employees last; that Kern was “AAA” rated; that Levolor had a policy of rating each employee before deciding on layoffs; and that Kern was not given a rating. Trial exhibits indicated that layoff decisions were based solely on the employee’s “grade” (AAA, A, B, etc.), “average” (production) and “points” (attendance). Seniority was not a determinative factor, either in the ratings actually made or as indicated by the Employee Handbook.
The evidence in favor of Levolor does not compel upsetting the jury’s verdict. The jury could have concluded from the evidence that Levolor had impliedly promised Kern that she would be treated fairly and would not be laid off except in accordance with the policies stated in the Employee Handbook and by the procedures applied equally to all employees. Although the Handbook states explicitly that it “is not a contract of employment,” Kern does not rely exclusively on the Handbook nor argue that an express contract is embodied in the Handbook. Instead, Kern argued that an implied contract existed, proved in part by the Handbook but more importantly, by the actual personnel policies and practices of Levolor.
2. Breach of Contract
Levolor argues that even if it had a contract with Kern, it was not breached. It bases this argument on evidence tending to show that Kern was laid off for the legitimate business reason of a reduction in force due to economic conditions. See Malmstrom v. Kaiser Aluminum and Chemical, 187 Cal.App.3d 299, 231 Cal.Rptr. 820 (1986). However, there was evidence that even if Kern was laid off in order to reduce the workforce, Levolor nevertheless laid her off in violation of its express and implied promises to follow certain procedures and hierarchies in determining which employees would be laid off first. Especially probative was evidence that Kern was the only “AAA” employee involuntarily laid off at that time; that she was not included in meetings to discuss layoffs; that she was never given a “golf score,” which Levolor used to determine layoffs; that Levolor based its decision in part on Kern’s lack of seniority, although seniority was not a factor in ranking other employees; and that Levolor did not consider transferring Kern to a different department, although other employees were [777]*777transferred rather than laid off. This evidence was sufficient to support a verdict in favor of Kern.
B. Good Faith and Fair Dealing
Under California law, every contract includes a covenant of good faith and fair dealing, which requires that neither party “do anything which will deprive the other of the benefits of the agreement.” Seaman’s Direct Buying Service, Inc. v. Standard Oil Co., 36 Cal.3d 752, 206 Cal.Rptr. 354, 362, 686 P.2d 1158, 1166 (1984). The covenant requires cooperation in carrying out the contract and honesty in creating or settling disputes. See 1 Witkin, Summary of California Law 674-76 (9th ed. 1987). In the employment setting, a breach can be shown “where the employee can establish lengthy satisfactory service and that the employer acted contrary to its own policies in discharging the employee.” See Sorosky v. Burroughs Corp., 826 F.2d 794, 802 (9th Cir.1987) (construing California law). There was sufficient evidence to allow this issue to be decided by the jury.
C. Age Discrimination
Levolor argues that Kern failed to establish a prima facie case of age discrimination. It appears from our review of the transcript that no, or virtually no, evidence was presented tending to show that Levo-lor treated Kern as it did because of her age. We do not, however, deem it necessary to resolve this question because the verdict is supported by the contractual claims discussed above.
D. General Verdict
As a general rule, “a general jury verdict will be upheld only if there is substantial evidence to support each and every theory of liability submitted to the jury.” Syufy Enterprises v. American Multicinema, Inc., 793 F.2d 990, 1001 (9th Cir.1986); see also Sunkist Growers, Inc. v. Winckler & Smith Citrus Products Co., 370 U.S. 19, 29-30, 82 S.Ct. 1130, 1135-36, 8 L.Ed.2d 305 (1962). However, we may construe a general verdict as attributable to one of several theories if it was supported by substantial evidence and was submitted to the jury free from error. Traver v. Meshriy, 627 F.2d 934, 938 (9th Cir.1980).2 The factors we must consider in deciding whether to exercise this discretion are: (1) the potential for confusion of the jury; (2) whether the losing party’s defenses apply to the count upon which the verdict is being sustained; (3) the strength of the evidence supporting the count relied upon to sustain the verdict; and (4) the extent to which the same disputed issues of fact apply to the various legal theories. Id. at 938-39.
We find this an appropriate case for the exercise of discretion. There was little potential for confusion. Kern’s counsel stressed the contractual bases for recovery in her closing argument. Age discrimination was offered not as an independent ground for recovery, but only as a possible explanation for Levolor’s disparate treatment of Kern. [R.T. 7/29 at 146-48.] The same factual predicate—that Kern was, without adequate explanation treated differently from other employees—necessary to find age discrimination would support a verdict in favor of Kern on her contractual theories. See Traver, 627 F.2d at 939 (no need to reach sufficiency of evidence for weak section 1983 claim where that claim “all but derivative” of state tort claims); see also Roberts v. College of the Desert, 870 F.2d 1411, 1417 (9th Cir.1988) (no need to reach sufficiency of evidence on discrimination theory in employment dispute where there was sufficient evidence of due process violation). Levolor’s defenses were the same for both the contractual and age discrimination claims: it argued that Kern was treated in accordance with company policy and was discharged for a legitimate business reason. The jury could not have found in favor of Kern under any of her theories without rejecting these defenses. [778]*778The evidence supporting the contractual theories of recovery, while not overwhelming, was strong. The facts used by Kern to support her theories of recovery were largely identical, except that her claim of age discrimination required additional evidence to support Kern’s theory of Levolor’s motive. The same facts that bore on the circumstances of her discharge were relevant to each of her theories.
II.
WEIGHT OF THE EVIDENCE
Levolor argues that, even if JNOV would not have been proper, the district court should at least have ordered a new trial on the ground that the verdicts on liability and damages were against the manifest weight of the evidence. This is a discretionary action on the part of the district court. William Inalis, 668 F.2d at 1027.
Levolor’s argument that the district court abused its discretion in denying it a new trial on the issue of liability hinges, of course, on the same evidentiary arguments discussed above. On Kern’s contractual claims, refusal to grant a new trial was not an abuse of discretion. The contractual claims being adequate to support the judgment, the age discrimination claims need not be discussed.
Levolor makes a distinct challenge to the amount of damages. The jury originally returned a verdict in favor of Kern for $237,000. The district court considered this amount “outrageous” and “weird”, E.R. 32, and indicated its intent to grant a new trial if Kern refused to accept a remit-titur. Id. The court initially indicated that it felt $60,000 would be an adequate amount. Id. After further consideration, the court proposed a remittitur resulting in a judgment of $137,000. [R.T. 10/01 at 10-13.] Kern accepted the remittitur.
The court did not abuse its discretion in calculating this remittitur. There was evidence that Kern’s total economic damages through age 65, when she planned to retire, were $110,000. [Exhibit 121]. There was evidence that Kern incurred $2,500 in consequential expenses moving to Ohio. It appears that the district court erroneously included as consequential damages $6,000 in costs incurred by Kern in traveling back to California to litigate her claim. [R.T. 10/01 at 11-12.] We also doubt that damages for stress could properly be awarded as consequential damages in this case. However, we affirm the remittitur on the ground that the expert testimony on future economic conditions was necessarily speculative. The expert himself testified his calculation was conservative. [R.T. 7/27 at 88.] Therefore, it was not reversible error to award Kern somewhat more than the dollar figure the expert suggested. See Chalmers v. City of Los Angeles, 762 F.2d 753, 760 (9th Cir.1985) (if damage award is supportable, it will not be disturbed on appeal unless grossly excessive, monstrous, or shocking to the conscience.)3
III.
MITIGATION OF DAMAGES
Levolor argues that Kern failed to mitigate her damages. Under California law, an employer’s liability is reduced by the amount the employee earned or with reasonable diligence could have earned after her discharge. The employer bears the burden of proving that “comparable, or substantially similar,” employment was available to the employee; the employee is not required to prove mitigation. Parker v. Twentieth Century-Fox Film Corp., 3 Cal.3d 176, 181-82, 89 Cal.Rptr. 737, 740, 474 P.2d 689, 692 (1970). Levolor failed to carry its burden. By contrast, Kern testified that she looked for work regularly for six months, until physical and emotional disorders prevented further searching. [779]*779[R.T. 6/30 at 27-28; R.T. 7/27/87 at 112-13.] Although Levolor asserts that it offered Kern her job back, it did not in fact do so: it merely indicated its desire to discuss a job opening with her. [S.E.R. 79.] This invitation came after Kern had moved to Ohio.4 The court did not clearly err in concluding that Levolor had failed to prove that Kern did not adequately mitigate her damages.
IV.
JUDICIAL MISCONDUCT
The district court judge made various comments which Levolor asserts damaged its case. These were as follows:
1. First, in a colloquy over an evidentia-ry motion, discussing the relevance of Le-volor’s evidence that other individuals over 50 years of age were not laid off, to disprove age discrimination, the following exchange took place:
The Court: Sure. They got preferential treatment somehow.
Mr. Brown [for Levolor]: So there’s no age discrimination.
The Court: There is age discrimination. They discriminated against this lady and didn’t layoff the others.
Mr. Brown: Your Honor, I differ on that. The Court: I know you do. But you differ on everything. You know, you come from Chicago, don’t you?
Mr. Brown: I do.
The Court: Yeah, contentious Chicago. Come on.
[E.R. 26.] This exchange occurred in front of the jury.
2. Levolor also objects to the district court’s comments during Levolor’s examination of a witness:
Q: Could you tell us what that figure [rate of production] means?
A: She worked 143 days for an hour more and I took the 143 days and divided the number of hours that she had written that she had worked into that 143. And then it was multiplied by 7.5, which is the hours that she had worked, which is the hours for the whole day, and it came out to 28.8 wands per day.
The Court: What on earth has that got— that’s time, not rate of production.
Mr. Brown: Let me follow up because I think—
The Court: So idiotic.
Mr. Brown: Leslie just forgot to tell us one thing.
The Court: I’m getting sick of it. If you don’t start getting on something else I may sanction you by issuing a judgment in the favor of the plaintiff. I’m getting sick of it.
[E.R. 23].
3.Finally, during examination of a witness concerning the meaning of “termination” and “layoff,” the court instructed the jury that the terms “layoff”, “discharge”, “quitting”, and “termination” all have different meanings, as a matter of law. [E.R. 16, 17, 24.] Levolor objected. [E.R. 16.] Levolor argues that this instruction was crucial because Kern argued that her “termination” by Levolor was key evidence of Levolor’s breach. However, any possible prejudice to Levolor was offset by the court’s instruction to the jury that “[Kern], was not terminated for layoff. She was laid off.” [E.R. 17.]
Levolor does not allege that it moved for a mistrial based on Judge Hauk’s misconduct. Levolor did, however, move for a new trial. Levolor objected to the court’s remarks concerning age discrimination and the “layoff/termination” distinction.
Litigants are entitled to a judge who is detached, fair and impartial. Shad v. Dean Witter Reynolds, Inc., 799 F.2d [780]*780525, 531 (9th Cir.1986). The standard for reversal on the basis of judicial misconduct in a civil trial is, nevertheless, quite high. Comments by the judge require reversal if the judge expresses his opinion on an ultimate issue of fact in front of the jury or argues for one of the parties. Id. Reversal will not be required where the judge emphasizes evidence; nor where the judge expresses skepticism, provided that the witness has an opportunity to respond. Id. Cutting comments to counsel, particularly those relating to skill rather than good faith or integrity, will not generally mandate reversal. Id.
The difference between comments which mandate reversal and comments which do not is demonstrated by Ward v. Westland Plastics, Inc., 651 F.2d 1266, 1271 (9th Cir.1980) and Maheu v. Hughes Tool Co., 569 F.2d 459, 469-71 (9th Cir.1977). In Maheu, plaintiff was suing for libel. Thus, his character was hotly in issue. At the end of the jury instructions, the judge discussed the plaintiff’s credibility and character in a manner which we deemed a judicial comment on character, virtually directing a verdict for plaintiff despite considerable impugning evidence. The judge’s comments were found to be reversible error.
In Ward, the judge demeaned the quality and relevance of much of plaintiff’s evidence and suggested nondiscriminatory motivations the defendant might have had: The judge seldom spoke directly to ultimate issues, and cautioned the jury that his remarks were not evidence. We declined to reverse. In reaching our conclusion we did not, however, focus primarily on the nature of the remarks: the most important factor in our decision to affirm was our perception that plaintiff’s case was too weak for the comments to have prejudiced it.
Even taking all of the district court’s comments together, we conclude there was no reversible error in this case. Levolor has failed to explain how the court’s comments about “layoff” and “termination” prejudiced its case. The judge’s occasional commentary on Chicago lawyers and on the flaws in Levolor’s witnesses’ testimony did not go to the merits. Upon our review of the trial as a whole, we cannot say that the district court judge appeared to favor one side over the other by his comments.
The judge’s comments about age discrimination, taken out of context, could be misunderstood. However, the context of the comments makes it clear that the judge was simply explaining his evidentiary ruling: that evidence that other workers had not been laid off did not mean that Kern was not discriminated against. In light of the adequate evidence to support the verdict on the contractual theory, we conclude that Levolor was not prejudiced by this remark.
V.
EVIDENTIARY ERROR
Evidentiary rulings are reviewed for abuse of discretion. Coursen v. A.H. Robins, 764 F.2d 1329, 1333 (9th Cir.1984). Error mandates reversal only if it probably affected the verdict. Haddad v. Lockheed California Corp., 720 F.2d 1454, 1459 (9th Cir.1983).
Levolor assigns error to two rulings. First, it argues that the court improperly excluded as irrelevant testimony from a Levolor employee who had trained Kern. That employee would have testified about the skills required for other jobs at Levolor. However, the witness had already testified that, in her opinion, Kern was not qualified for any other job at Levolor. [E.R. 29]. The court was within its discretion in determining that nothing more would be gained from a detailed description of numerous other jobs at Levolor.
Levolor also challenges the exclusion of testimony from its Corporate Manager of Personnel. This testimony, according to Levolor, would have explained the “profit sharing letter” Kern received, which contained the word “terminated”. [R.T. 7/29 at 88-89.] This testimony was properly excluded on grounds of competency. Levolor’s witness did not hold a position with Levolor until after the relevant time period, and therefore lacked personal knowledge concerning the interpretation of [781]*781a letter Kern received before the witness became affiliated with the company.
VI.
JURY INSTRUCTIONS
A district court’s formulation of jury instructions is reviewed for an abuse of discretion, so long as its statement of the law is correct. United States v. Wellington, 754 F.2d 1457, 1463 (9th Cir.1985). Error will not require reversal if it is more probably than not harmless. Haddad v. Lockheed California Corp., 720 F.2d 1454, 1459 (9th Cir.1983).
Levolor asserts that the district court should have given its proposed instruction on mitigation of damages, which stated that Kern would not be entitled to damages after failure to accept a substantially equivalent job from Levolor or after she dropped out of the job market. [E.R. 35 (proposed instruction); 14-15 (rejection of proposed instruction)]. Instead, the court gave the following instruction:
An employee who was damaged as a result of a breach of an employment contract by the employer, has a duty to take steps to minimize the loss by making a reasonable effort to find comparable employment.
If the employee through reasonable efforts could have found comparable employment, any amount that the employee could reasonably have earned by obtaining comparable employment through reasonable efforts shall be deducted from the amount of damages awarded to employee.
[S.E.R. 131]. This is a correct statement of California law. See Parker v. Twentieth Century-Fox Film Corp., 3 Cal.3d 176, 89 Cal.Rptr. 737, 740, 474 P.2d 689, 692 (1970). There was no error in giving the instruction. Levolor’s proposed instruction, by contrast, was misleading because there was no evidence that Levolor had actually offered Kern her job back.
CONCLUSION
There was substantial evidence to support the verdict and judgment on Kern’s contractual claims. The award of damages was not clearly erroneous. Comments by the district court judge were not prejudicial to Levolor. The evidentiary rulings were not error. The jury instruction on mitigation was an accurate statement of the law. The judgment is AFFIRMED.