Task: songer_suffic

What follows is an opinion from a United States Court of Appeals. The issue is: "Did the court rule that there was insufficient evidence for conviction?" Answer the question based on the directionality of the appeals court decision. If the court discussed the issue in its opinion and answered the related question in the affirmative, answer "Yes". If the issue was discussed and the opinion answered the question negatively, answer "No". If the opinion considered the question but gave a mixed answer, supporting the respondent in part and supporting the appellant in part, answer "Mixed answer". If the opinion does not discuss the issue, or notes that a particular issue was raised by one of the litigants but the court dismissed the issue as frivolous or trivial or not worthy of discussion for some other reason, answer "Issue not discussed". If the opinion considered the question but gave a "mixed" answer, supporting the respondent in part and supporting the appellant in part (or if two issues treated separately by the court both fell within the area covered by one question and the court answered one question affirmatively and one negatively), answer "Mixed answer". If the opinion either did not consider or discuss the issue at all or if the opinion indicates that this issue was not worthy of consideration by the court of appeals even though it was discussed by the lower court or was raised in one of the briefs, answer "Issue not discussed". If the court answered the question in the affirmative, but the error articulated by the court was judged to be harmless, answer "Yes, but error was harmless". 

OPINION OF THE COURT
HUTCHINSON, Circuit Judge.
Co-defendants Gerald A. Leo (Leo) and James Badolato (Badolato) appeal from judgments of conviction and sentence entered against them following a jury trial in the United States District Court for the Eastern District of Pennsylvania. For the reasons set forth below, we will affirm the judgments.
I.
On November 29, 1988, a grand jury sitting in the United States District Court for the Eastern District of Pennsylvania handed up a 321-count indictment against Leo, Badolato and General Electric Corporation (General Electric), doing business as Management and Technical Services Company (MATSCO), on various charges related to alleged defense contract fraud and an alleged cover-up that followed. MATSCO was charged with five counts of mail fraud, see 18 U.S.C.A. § 1341 (West Supp.1991), and 312 counts of violating the criminal False Claims Act, see 18 U.S.C.A. § 287 (West Supp.1991). Leo was charged with five counts of mail fraud, one count of racketeering, see 18 U.S.C.A. § 1962 (West 1984 & Supp.1991), and two counts of making false statements to government agencies, see 18 U.S.C.A. § 1001 (West 1976). Badolato was charged with five counts of mail fraud, one count of racketeering, one count of making a false statement to a government agency and one count of endeavoring to obstruct Defense Department proceedings, see 18 U.S.C.A. § 1505 (West 1984).
Jury selection began on October 30, 1989, and the trial commenced on November 14, 1989. Testimony at trial did not conclude until January 22, 1990. On February 2, 1990, the jury returned its verdict. It convicted MATSCO on four counts of mail fraud and 282 counts of violating the False Claims Act. It convicted Leo on four counts of mail fraud and one count of making a false statement; at the close of its case, the government had dismissed the other false statement charge against Leo. The jury also convicted Badolato on one false statement count and on the count that charged him with endeavoring to obstruct agency proceedings.
On July 26, 1990, the district court sentenced the three defendants. It accepted a joint recommendation from the government and MATSCO that MATSCO be sentenced to pay a $10,000,000.00 criminal fine. As part of the agreement, the government says that General Electric paid an additional $8,300,000.00 in civil damages and $11,-700,000.00 to resolve other civil matters. General Electric also agreed not to appeal the district court’s judgment of conviction and sentence. The district court sentenced Leo to ten months imprisonment on the mail fraud charges and ordered him to pay a $15,000.00 fine on the false statement conviction. The district court sentenced Badolato to five months imprisonment on the charge of endeavoring to obstruct agency proceedings and ordered him to pay a $10,000.00 fine on his false statement conviction.
As required when reviewing convictions, we recite the relevant facts in the light most favorable to the government. Cf Glasser v. United States, 315 U.S. 60, 80, 62 S.Ct. 457, 469, 86 L.Ed. 680 (1942). The testimony at trial focused on a contract between the United States Army and MAT-SCO for the production of mobile battlefield computer systems housed in trailer-like vans. The system was called the Decentralized Automated Service Support System, more commonly known as DAS-3B. The indictment charged that Leo, a long-time General Electric employee who was responsible for the management of the materials and purchasing department for MATSCO, and Badolato, who was MAT-SCO’s subcontracts manager, executed a scheme to defraud the Army out of millions of dollars on the contract in order to advance their standing within the company. Further, the indictment alleged that, after the contract between the Army and MAT-SCO was signed in June of 1983, Leo and Badolato committed various acts to hide the fraud from the Defense Department.
In 1979, the Army awarded MATSCO a competitive contract to build mobile computer systems that could be housed in trailer-like vans and used for logistical support for Army units around the world. The Army sent a team of specialists to the MATSCO plant in 1982 to assist in the development of an updated version of the van.
The contract called on MATSCO to produce 233 of the DAS-3B vans over five years. The contract also gave the government the option to purchase twenty-five more in the sixth year. It was known as a “firm fixed price contract.” As we will now explain, the “firm fixed price” is initially not so firm and fixed. The 1962 amendments to the Armed Services Procurement Act of 1947 (Act), Pub.L. No. 87-653, 76 Stat. 528 (1962) (codified in scattered sections of 10 U.S.C.A.), and regulations promulgated under the Act applied to MATSCO’s contract with the Army. Under the Act, a contractor must furnish the procuring agency a proposal that includes the contractor’s best estimate of the costs the contractor expects to incur in making the product. See 10 U.S.C.A. § 2306(f)(1) (West 1983). Thus, the contractor must give its best estimate of anticipated material costs, labor, overhead, general and administrative expenses and then show its anticipated profit. The government and the contractor then negotiate over the amount of these projections as well as the appropriate percentage of total cost that should be added for profit in arriving at the final price. If the contractor’s costs change before a final agreement is reached, the contractor must inform the Army. Once a final agreement is reached, the contractor must provide the Army with a Certificate of Current Cost, which certifies that all of the cost information provided to the Army as of the date of the final agreement is accurate, current and complete.
MATSCO’s proposal on the DAS-3B contract was first submitted to the Army on January of 1983. MATSCO submitted a revised proposal in March of 1983. In accord with the instructions for the proposal, MATSCO promised the Army that it would update the prices upon which the proposal was based as negotiations with subcontractors continued.
The subcontract component of the proposal amounted to $156,715,300.00, based upon quotations received from subcontractors. The largest subcontract covered the Honeywell Information Systems computers to be placed into the vans. Aside from the computers, the March, 1983 proposal contained about $67,000,000.00 in estimated subcontract costs for thirty other subcontractors.
Leo's job at General Electric was purchasing for government contracts. He testified at trial that one of his strong points that helped him in that job was his vast knowledge of procurement and subcontract procedures and regulations, both government and commercial. See Joint Appendix (Jt. App.) at 837f. Among Leo’s responsibilities was the preparation of updates on the proposal’s cost estimates throughout the negotiation process. Leo testified that if the General Electric personnel principally responsible for negotiations with the Army over costs and prices needed any information about a subcontract’s status, they would have to come to him.
Occasionally during the negotiations, Army negotiators asked General Electric negotiators whether there were any expected reductions in the subcontractor costs. The General Electric negotiators answered that with the exception of the Honeywell subcontract, there were no major reductions in subcontractor costs expected. This answer was based upon the information Leo relayed to General Electric negotiators.
On April 13, 1983, Leo himself briefed the Army negotiators. He told them that since the March, 1983 proposal certain subcontractor costs had gone up while others had gone down. On May 3 and 4, 1983, the Army and General Electric negotiated over the final estimate of subcontractor costs. During these final negotiations, Leo again represented that subcontractor costs apart from the Honeywell subcontract were basically unchanged from the March, 1983 estimate. Leo also proposed an additional $4,200,000.00 in subcontract costs he said were needed to cover what he called a “scope increase,” which represented additional requirements not included in the March 1983 cost proposal.
Based on Leo’s representation that subcontractor costs other than Honeywell’s would remain about the same, the Army and General Electric agreed to a proposal under which MATSCO would reduce the $67,000,000.00 in proposed subcontract costs, which did not include Honeywell’s cost, by six percent and would reduce the $4,200,000.00 scope increase by eight percent. Thus, the Army agreed to pay nearly $67,000,000.00 for the thirty subcontractors other than Honeywell. At the close of negotiations, Leo told the Army negotiators that the proposed reduction of expenses would be difficult to meet. On June 6, 1983, the date of the final price agreement, General Electric certified to the Army that as of June 2, 1983 all cost data were accurate, current and complete.
In fact, that was not the case. The government presented evidence at trial that Leo and Badolato had actually negotiated millions of dollars in subcontract savings between February of 1983 and June 2, 1983 without the Army’s knowledge. As of April 13, when Leo met with the Army negotiators, MATSCO had reduced its subcontract costs by $6,610,967.00. Thus, the government contended at trial that the information Leo provided to the Army negotiators that day was false and fraudulent. By May 4, 1983, when the final subcontract negotiations were taking place between General Electric and the Army, MATSCO had achieved savings of $10,650,797.00 on the proposed subcontract costs. The cost reduction proposal that Leo said on May 4, 1983 would be so difficult to meet had already been exceeded by more than $6,000,000.00. On June 2, 1983, just before the contract was finalized, MATSCO had pretty well assured itself of over $12,800,-000.00 in subcontract savings that had not been disclosed to the Army.
The government also introduced evidence that Leo and Badolato were responsible for inflating the March, 1983 revised proposal. Leo’s superiors instructed him to bid only on the known requirements, yet Leo, on two occasions, and Badolato, on one occasion, told subcontractors to pad their quotes in anticipation of unknown contingencies. Leo and Badolato never disclosed the padding to the Army. Nor was the Army informed later when these subcontractors removed the contingency padding from their prices. The government also introduced evidence to show that it was Leo who ran up the March, 1983 proposal by including $696,000.00 in premium costs for expedited delivery, even though the Army negotiators thought that it was the subcontractors themselves that had insisted on this cost item. At trial, the two subcontractors that testified denied requiring the premium.
In late October of 1983, the Defense Contract Audit Agency began a standard post-award audit of the DAS-3B contract to see whether the cost and price data submitted to the Army had been accurate, complete and current as of June 2, 1983. Supervisory auditor Carl Stern (Stern) headed the audit.
Stern began to audit subcontractor costs in the summer of 1984. Working out of the MATSCO department that contained Leo and Badolato’s offices, Stern began to review the purchasing files that Badolato had given him. In October of 1984, Stern noticed that many subcontracts had been placed before June 2, 1983 at prices less than those disclosed to the Army.
In November of 1984, Stern prepared a list of thirty subcontractors in which he included his conclusions about when particular purchase order prices had been firmly established. Stern gave the list to Leo and asked Leo to comment on the dates Stern had included. Before receiving Leo’s comments on the list, Stern noticed that the purchasing files were in Leo’s office. On December 14, 1984, a General Electric finance manager returned Leo’s version of the subcontract dates on a copy of Stern’s list to Stern. Leo had filled in all but a few of the dates. Leo’s dates indicated that subcontract prices for a number of subcontractors were not established until after May 4, 1983. Leo had earlier told other General Electric employees that these very same subcontractors had their prices established before May 4.
After learning of Stern’s initial findings on the timing of firm costs for subcontracts, General Electric finance executive Michael Kennedy (Kennedy) began a separate review of the purchasing files. While seeking information regarding the future year prices for a particular vendor, Kennedy checked the finance department’s copy of a purchase order. He compared the purchase department’s files with copies of the same information in the finance department’s files. He found the purchasing department’s order dates differed from the finance department’s copy. This aroused his suspicion. Twice he asked Leo and Badolato about the discrepancies. Both times each expressed surprise.
On January 15, 1985, Badolato changed his story. He told Kennedy that in January of 1984 he altered eight purchase orders placed before June 2, 1983, to reflect dates after June 2, 1983. Badolato told Kennedy that Leo had no knowledge of this and that Stern’s audit had nothing to do with the changes. Instead, Badolato claimed he altered the dates because of a late 1983 unrelated review of MATSCO’s purchasing system by another Defense Department division. As it turned out, Bado-lato had altered about fourteen documents in January of 1984. These alterations caused other purchasing personnel to place incorrect dates on amendments made to those fourteen orders. All told, this resulted in about forty documents bearing false purchase dates.
Badolato’s reason for altering the dates was disputed. Defense Department analysts who conducted the purchasing system review in 1983 testified that eight of the purchase orders Badolato altered in January 1984 were reviewed in the summer of 1983, at which time the Defense Department analysts told Badolato that they did not intend to look at these purchase orders again.
After Badolato had made his initial ac-knowledgement to Kennedy, it was discovered that Badolato had also altered two copies of purchase orders bearing the signature of subcontractor representatives. Badolato had also asked three vendors to provide MATSCO with false certificates of current costs. Leo joined Badolato in one of these requests.
II.
The district court exercised jurisdiction over the charges against Leo and Badolato pursuant to 18 U.S.C.A. § 3231 (West 1985). We have jurisdiction over these appeals pursuant to 28 U.S.C.A. § 1291 (West Supp.1991).
Leo raises five issues on appeal. First, he contends that the government failed to produce sufficient evidence to support his conviction for having made a false statement. Second, he argues that the district court abused its discretion and erred as a matter of law in permitting General Electric finance executive Kennedy to testify about his audit of the DAS-3B contract. Third, he asserts that the district court violated his constitutional right to mount a complete defense when it limited his ability to deny the motive for wrongdoing that the government alleged. Fourth, Leo contends that the district court abused its discretion in excluding testimony from another General Electric auditor that he believed Leo over another witness. Leo's final argument is that the district court abused its discretion in allowing expert testimony concerning industry customs and practices in the field of defense contracting. If we rule in favor of Leo on any of his evidentiary arguments, he asks that we grant him a new trial.
Badolato raises two arguments in his appeal. First, he contends that the count charging him with obstructing proceedings before the Defense Department failed to charge a criminal offense. In his other argument, Badolato claims that the district court erred in refusing to give the jury his proposed instruction to consider his later correction of his false statements in deciding whether he made the false statements intentionally. This correction occurred, Ba-dolato argues, when he admitted having made purchase order alterations to Kennedy. MATSCO officials then informed the Army of the alterations.
On Leo’s sufficiency issue, we view the evidence in the light most favorable to the government as the winner of the jury verdict. So considering the record, we then determine whether there was sufficient evidence for a rational jury to find beyond a reasonable doubt that Leo was guilty of having made a false statement. See United States v. Gonzalez, 918 F.2d 1129, 1132 (3d Cir.1990), cert. denied, — U.S. -, 111 S.Ct. 1015, 112 L.Ed.2d 1097 (1991).
Leo’s remaining four issues all relate to rulings on the admission of evidence. We review them for abuse of discretion, rejecting Leo’s argument that we should exercise plenary review over the district court’s relevancy rulings in accord with a statement in In re Japanese Elec. Prods. Antitrust Litig., 723 F.2d 238, 269 (3d Cir.1983), rev’d on other grounds sub nom. Matsushita Elec. Indus. v. Zenith Radio Corp., 475 U.S. 574, 106 S.Ct. 1348, 89 L.Ed.2d 538 (1986). In Pfeiffer v. Marion Center Area School Dist, 917 F.2d 779, 781 (3d Cir.1990), we determined that the statement in Japanese Elec. Prods, that relevancy rulings would receive plenary review conflicted with an earlier holding of our Court and thus would be deemed to be without effect. See also United States v. Eufrasio, 935 F.2d 553, 571 (3d Cir.1991). Therefore, we will use the abuse of discretion standard in our review of all of the evidentiary rulings at issue here.
We exercise plenary review over whether the count of the indictment that charged Badolato with obstructing Defense Department proceedings charged an offense under the law. See United States v. Markus, 721 F.2d 442, 443 (3d Cir.1983). Finally, with regard to the district court’s decision to refuse Badolato’s proposed instruction about his correction of earlier untruths, we review the decision under an abuse of discretion standard. In the course of making that determination, we will look to see whether the proffered instruction was legally correct, whether it was not substantially covered by other instructions and whether its omission prejudiced him. See United States v. Smith, 789 F.2d 196, 204 (3d Cir.), cert. denied, 479 U.S. 1017, 107 S.Ct. 668, 93 L.Ed.2d 720 (1986).
III.
A.
Leo first argues that the evidence, even when taken in the light most favorable to the government, does not meet the substantial evidence test necessary to uphold the jury’s determination that he was guilty of the charge that he made a false statement in a false writing or that he concealed material facts by trick, scheme or device, in violation of 18 U.S.C.A. § 1001 (West 1976). Section 1001 provides:
Whoever, in any matter within the jurisdiction of any department or agency of the United States knowingly and willfully falsifies, conceals or covers up by any trick, scheme, or device a material fact, or makes any false, fictitious or fraudulent statements or representations, or makes or uses any false writing or document knowing the same to contain any false, fictitious or fraudulent statement or entry, shall be fined not more than $10,000 or imprisoned not more than five years, or both.
Id.
The false statement count of the indictment for which Leo was convicted charged that he:
submitted a schedule to the Army contracting officer and the [Defense Contract Audit Agency] which represented the specific dates of the contract negotiation with subcontractors when in truth and fact... Leo... well knew that: (1) altered and falsified documents were submitted to the [Audit Agency] auditors to conceal the true negotiation dates; and (2) “Contingencies” were routinely used to inflate cost and pricing data in the contract pricing proposals of subcontracts under audit.
Jt.App. at 57.
The government presented the following evidence at trial: supervisory auditor Stern testified that he gave Leo a list of subcontractor bid dates in November of 1984 and asked Leo to comment on the accuracy of these dates. Stern received Leo’s response on December 14, 1984, three days after Stern presented his informal findings at a meeting of MATSCO representatives, which included Badolato.
The government also argues that the format of Stern’s list made it clear to Leo that Stern wanted Leo to confirm or deny the accuracy of Stern’s conclusions about the dates the thirty listed subcontracts became firm as to price. The column to which Leo was to respond was marked “Date P.O. [purchase order] price established.” Jt. App. at 330. That is the very column to which Leo did in fact respond. Further, Leo admitted in a handwritten memo from late 1985, which conflicted with the testimony he gave at trial, that he understood that he was given the list to advise Stern if Stern’s numbers and dates were correct. Thus, the government argues that there was substantial evidence that Leo knew that Stern expected to receive from Leo the correct dates on which purchase order prices were established.
While Leo claims there was no evidence to show that he knew Badolato had altered the date of one particular subcontract with Avanti, the government introduced evidence that Leo knew that five other subcontractors had firm subcontract prices before May 4, 1983, the date of final negotiations over subcontractor costs. Nevertheless, in his response to Stern’s list Leo stated that the dates of three of these five other subcontracts did not become firm until late May of 1983. If, as we must assume, the jury believed the government’s evidence that Leo knew all five of these other subcontracts were firm before May 4, Leo’s defense that he did not know there were savings achieved between May 4 and June 2, 1983 that were undisclosed to the Army collapses since the jury could infer Leo knowingly failed to disclose significant savings that had been achieved before May 4. This explains why Leo tried to push until after May 4 as many dates as possible on the list Stern provided.
With respect to the Avanti contract, the government sought to convince the jury that Leo had willfully turned a blind eye to whether the purchase order date he reported on Stern’s list was the actual date the purchase order was established. The government produced evidence at trial that Stern, when reviewing the MATS CO purchasing files, noticed that the initial Avanti purchase order bore the date June 8 but that a spare parts contract for the very same product bore the date May 13. General Electric finance executive Michael Kennedy testified that when he reviewed the same files as Leo and saw this inconsistent information, he checked the finance department’s copies of the files and found eight altered purchase orders, including the Avanti contract. The government thus argued at trial that Leo’s testimony, that he did not notice the discrepancy, should not be believed given his extensive, twenty-year background in purchasing for government contracts.
Next, the government notes that by Leo's own admission Stern asked him to certify whether the subcontractor costs on the list were correct. In response, Leo failed to state that the costs on the list included padding for contingencies, an expense that Leo never reported to the Army. Thus, the government contends that sufficient evidence exists to prove Leo’s concealment of material facts. Leo argues that he had no affirmative duty to disclose the inclusion of contingencies. However, the contract itself clearly requires General Electric, and therefore its agents, to provide current, accurate and complete cost information.
Finally, Leo argues that he did not know that the list would be returned to the Defense Department. However, in United States v. Yermian, 468 U.S. 63, 73, 104 S.Ct. 2936, 2941, 82 L.Ed.2d 53 (1984), the Supreme Court held that a defendant’s actual knowledge that his false statement would be transmitted to a government agency is not an essential element of a false statement offense under 18 U.S.C.A. § 1001, the statute at issue here. Leo’s argument that he lacked knowledge his statement would be returned to the Defense Department is not a ground for acquittal unless Yermian is distinguishable.
Leo claims that while Yermian did hold that actual knowledge was not required by § 1001, the Court did not foreclose the necessity of proving a lesser mental requirement of reasonable belief or at least foreseeability. Leo is correct. However, in the wake of Yermian, four of our sister courts of appeals have held that § 1001’s requirement of federal involvement is merely jurisdictional and that “no mental state is required with respect to federal involvement in order to establish a violation of § 1001.” United States v. Bakhtiari, 913 F.2d 1053, 1060 (2d Cir.1990), cert. denied, — U.S. -, 111 S.Ct. 1319, 113 L.Ed.2d 252 (1991); see United States v. Gibson, 881 F.2d 318, 323 (6th Cir.1989); United States v. Suggs, 755 F.2d 1538, 1542 (11th Cir.1985); United States v. Green, 745 F.2d 1205, 1209 (9th Cir.1984), cert. denied, 474 U.S. 925, 106 S.Ct. 259, 88 L.Ed.2d 266 (1985).
We agree with those courts and hold that the plain language of § 1001 and the thrust of the majority opinion in Yermian demonstrate, as the court wrote in Bakhtiari, “that no culpability standard is applicable with regard to the jurisdictional element of the statute.” 913 F.2d at 1061 (emphasis in original). For this reason, we hold that Leo’s alleged lack of knowledge of federal jurisdiction does not provide grounds for setting aside the jury’s verdict on the false statement count.
After the jury returned a general verdict finding Leo guilty on the false statement count, the district court asked the jury to determine the theory under which it had unanimously found Leo guilty. The jury answered the district court’s special interrogatory by stating that it had found both that Leo had made a false writing and that he had concealed material facts by scheme, trick and device. The government correctly notes that even if one theory is deficient, we must uphold the jury’s verdict so long as the other theory is adequately supported in the record. See United States v. Ryan, 828 F.2d 1010, 1019-20 (3d Cir.1987).
Viewing all of this evidence in the light most favorable to the government and having considered all the contentions of the parties with respect to the evidence described above, we hold that the evidence is sufficient to sustain Leo’s conviction on the charges that he had made a false writing and that he had concealed material facts by scheme, trick and device. While Leo, who testified in his own defense at trial, denied the crucial facts that the government put before the jury, the jury’s verdict shows that it believed the government’s version, not Leo’s. We must affirm Leo’s conviction on count nine “if a rational trier of fact could have found [him] guilty beyond a reasonable doubt and the convictions are supported by substantial evidence.” Gonzalez, 918 F.2d at 1132. For us to sustain the verdict against Leo, the evidence against him “does not need to be inconsistent with every conclusion save that of guilt.” Government of Virgin Islands v. Williams, 739 F.2d 936, 940 (3d Cir.1984) (quoting United States v. Allard, 240 F.2d 840, 841 (3d Cir.1957)). The government adduced ample evidence for a rational jury to find Leo’s guilty beyond a reasonable doubt under count nine of the indictment; therefore, we reject Leo’s argument that the evidence was insufficient to support his conviction for having violated 18 U.S.C.A. § 1001.
B.
Having examined Leo’s sufficiency argument, we pass to consideration of his evi-dentiary contentions and comment first on the issues he raises concerning the testimony of General Electric finance executive Kennedy.
Leo first argues that the district court abused its discretion in allowing Kennedy to testify about his audit of the DAS-3B contract. He also objects to several exhibits that the district court admitted into evidence during the government’s examination of Kennedy. The government responds by arguing that Kennedy’s testimony was admissible either as expert or lay opinion and defends the admission of the challenged exhibits.
In December of 1984, Kennedy began his audit of the DAS-3B contract, which soon became a regular part of his business activity. At that time, Kennedy had been a manager in finance for General Electric for over thirty years. Between 1981 and 1985, Kennedy managed General Electric’s Tactical Data Systems, which included MAT-SCO. While managing Tactical Data Systems, Kennedy performed financial analysis and forecasting, created and monitored budgets and plans and tracked costs and profits. Once MATSCO accepted the Army’s proposal to cut subcontractor costs, Tactical Data Systems attempted to keep track of the effort to meet this proposal.
In the audit he performed, Kennedy and two subordinates reviewed all material in the purchasing department’s files for the thirty MATSCO subcontractors. In his preliminary review, Kennedy noticed that many purchase order prices had been established before June 2, 1983, the key date on the certificate of current costs that MATSCO provided to the Army. Kennedy also met with Leo and received written comments from Leo. Leo agreed with most of Kennedy’s conclusions as to when subcontract purchase prices had been established.
Kennedy’s review continued through most of 1985. Kennedy testified at trial that his goal in the audit was to discover the truth. See Supplemental Appendix (Supp.App.) at 823. Based on Kennedy’s audit, General Electric decided to refund $3,690,500.00 to the United States.
1.
In its brief on appeal, the government first contends that Kennedy’s testimony was admissible as expert testimony. See Brief of Appellee at 27. It is well established that a district court has broad discretion over whether to recognize a witness as an expert. See Salem v. United States Lines, 370 U.S. 31, 35, 82 S.Ct. 1119, 1122, 8 L.Ed.2d 313 (1962); United States v. Vastola, 899 F.2d 211, 234 (3d Cir.1990) (quoting Salem), vacated on other grounds, — U.S.-, 110 S.Ct. 3233, 111 L.Ed.2d 744 (1990).
Here, the district court did not rule that Kennedy was qualified to give expert testimony. Instead, the district court held that Kennedy could testify to certain opinions he formed pursuant to Federal Rule of Evidence 701, which governs opinions offered by lay witnesses.
The reason the district court did not pass upon Kennedy’s qualification as an expert is that the government repeatedly contended before the district court that Kennedy would not be testifying as an expert. See Jt.App. at 515 (“This is not in the nature of expert testimony.”); Jt.App. at 605 (“If it is opinion testimony,... we cited two cases, your Honor, in which it was permitted for a non-expert to offer opinion based upon his review of business records.”).
In Vastóla we held that the government did not have to utter any formal incantation to request that its witness be admitted as an expert. Instead, we held that so long as the defendant is on notice that the witness would testify as an expert, the defendant cannot later be heard to argue that the government failed formally to ask that its witness’s opinions be admitted as those of an expert. Vastola, 899 F.2d at 234.
The government’s argument that we should now qualify Kennedy as an expert turns Vastóla upside down. Instead of placing Leo on notice that Kennedy would be testifying as an expert, the government expressly informed Leo and the district court that Kennedy would not testify as an expert. At most, the government only once, in passing, referred to Kennedy as an expert in General Electric’s corporate structure on the alleged acts of wrongdoing because General Electric relied upon Kennedy’s audit in determining how much money to refund to the government as a result of the inflated cost of the DAS-3B program. See Jt.App. at 515.
As we recognized in Vastóla, whether to certify a witness as an expert is a fact-intensive question that we review under the abuse of discretion standard. Vastóla, 899 F.2d at 234. Usual trial practice requires the proponent of expert testimony to show the witness’s qualifications. The party opposing the expert witness is then given a chance to attack the witness’s qualifications as an expert and cross-examine him about them. The district judge may also question the witness before certifying him as an expert.
Here, the government never sought at trial to have Kennedy qualified as an expert witness. We agree with the Tenth Circuit that a party cannot seek to have a witness certified as an expert on appeal when the party did not seek to have the witness qualified as an expert before the district court. See United States v. Hoffner, 777 F.2d 1423, 1425 n. 1 (10th Cir.1985).
2.
The government, however, advances an alternate basis for admitting Kennedy's testimony. It contends that his testimony was proper under Federal Rule of Evidence 701. Rule 701, entitled “Opinion Testimony by Lay Witnesses,” provides:
If the witness is not testifying as an expert, the witness’ testimony in the form of opinions or inferences is limited to those opinions or inferences which are (a) rationally based on the perception of the witness and (b) helpful to a clear understanding of the witness’ testimony or the determination of a fact in issue.
Fed.R.Evid. 701. This rationale was advanced at trial, and the district court held that the opinions Kennedy gave during his testimony were admissible as lay opinion. We review the district court’s ruling that Kennedy’s opinions were admissible under Rule 701 for abuse of discretion. See Eisenberg v. Gagnon, 766 F.2d 770, 780 (3d Cir.), cert. denied, 474 U.S. 946, 106 S.Ct. 346, 88 L.Ed.2d 290 (1985).
Kennedy testified about the conclusions he formed while investigating General Electric’s purchasing department files. For example, after summarizing the documents, he explained how certain purchase order dates had been changed. His opinion testimony accordingly satisfied Rule 701(a)’s requirement that lay opinion testimony be “rationally based on the perception of the witness.” Fed.R.Evid. 701(a). Our Court has specifically held that lay opinion testimony can be based upon a witness’s review of business records. See Teen-Ed, Inc. v. Kimball Int'l, Inc., 620 F.2d 399, 403-04 (3d Cir.1980); see also In re Merritt Logan, Inc., 901 F.2d 349, 359-60 (3d Cir.1990); Eisenberg, 766 F.2d at 781.
Rule 701(b) requires lay opinion testimony to be “helpful.” Kennedy’s testimony was helpful in allowing the jury to synthesize and understand the many documents contained in the thirty subcontract files that he had examined. The district court did not abuse its discretion in deciding that Kennedy’s lay opinion testimony would be helpful to the jury in determining a fact in issue. This satisfies Rule 701’s second prong.
In Teen-Ed we stated that the “modern trend favors the admission of opinion testimony, provided that it is well founded on personal knowledge and susceptible to specific cross-examination.” Teen-Ed, 620 F.2d at 403. Here, the district court gave Leo wide latitude to cross-examine Kennedy. Leo’s attacks on Kennedy’s prior auditing experience and the manner in which he conducted this specific audit go to the weight, not the admissibility, of Kennedy’s testimony. The district court did not abuse its discretion in admitting Kennedy’s testimony as lay opinion.
3.
Leo also claims the district court erred with respect to four exhibits that the government introduced through Kennedy. The first is a chart containing Kennedy’s findings that Kennedy’s boss, Robert Morris

Question: Did the court rule that there was insufficient evidence for conviction?
A. No
B. Yes
C. Yes, but error was harmless
D. Mixed answer
E. Issue not discussed
Answer:

Answer: A