*1193*527{¶ 1} This is an appeal from a judgment of the Tenth District Court of Appeals denying a writ of mandamus to an Ohio prisoner. The prisoner alleges that his parole-board file contains inaccurate information; he seeks to have the parole board correct the information in his file and hold a new parole hearing. We conclude that he has failed to meet his burden to present a credible allegation of a substantive inaccuracy in the information contained in his file. As a consequence, we affirm the judgment of the Tenth District Court of Appeals denying the writ.
Background
{¶ 2} Michael Cobb is serving a prison sentence of 18 years to life for his 1998 convictions for robbery and murder with a gun specification. Cobb attended an Ohio Parole Board hearing on June 11, 2015, after which the board denied his request for parole. In reaching its decision, the parole board noted that Cobb exhibited "good insight into his crimes" and "did display remorse for his actions." But the board also expressed concern over Cobb's "problematic conduct" during his incarceration and determined that "a release at this time would demean the *528serious nature of this crime," because "[t]he male victim in this offense was shot in the back by the offender and was then robbed of his property."
{¶ 3} Ohio Adm.Code 5120:1-1-07(A) provides that an inmate may be released at the time he becomes eligible for parole unless the parole board finds that continued incarceration is necessary for certain specified reasons. The board concluded that continued incarceration was necessary in Cobb's case on the following grounds:
(2) There is substantial reason to believe that due to the serious nature of the crime, the release of the inmate into society would create undue risk to public safety, or that due to the serious nature of the crime, the release of the inmate would not further the interest of justice nor be consistent with the welfare and security of society.
(3) There is substantial reason to believe that due to serious infractions of [Ohio Adm.Code 5120:9-06], the release of the inmate would not act as a deterrent to the inmate or to other institutionalized inmates from violating institutional rules and regulations.
See Ohio Adm.Code 5120:1-1-07(A).
{¶ 4} Cobb filed a complaint for a writ of mandamus in the Tenth District Court of Appeals in which he requested an order compelling the Ohio Adult Parole Authority ("APA") to correct five alleged inaccuracies in the records that the parole board relied on and to hold a new hearing. The gist of Cobb's claim is that the parole board might have granted his request for parole had it not relied on substantive errors in his file. In support of his claim, Cobb cites our decision in State ex rel. Keith v. Adult Parole Auth. , 141 Ohio St.3d 375, 2014-Ohio-4270, 24 N.E.3d 1132.
{¶ 5} The APA filed a motion to dismiss, and the Tenth District appointed a magistrate to hear the case. With regard to each of the five alleged inaccuracies, the magistrate determined that Cobb had failed to demonstrate a substantive error that may have influenced the parole board's consideration of parole. The magistrate therefore *1194recommended that the APA's motion1 be granted and Cobb's request for a writ be denied. The court of appeals adopted the magistrate's decision denying the writ. Cobb appealed to this court. *529Cobb has failed to show that he is entitled to a writ of mandamus
{¶ 6} To be entitled to a writ of mandamus, Cobb must establish by clear and convincing evidence (1) a clear legal right to the requested relief, (2) a clear legal duty on the part of the APA to provide it, and (3) the lack of an adequate remedy in the ordinary course of law. State ex rel. Waters v. Spaeth , 131 Ohio St.3d 55, 2012-Ohio-69, 960 N.E.2d 452, ¶ 6, 13.
{¶ 7} Cobb relies on our decision in Keith , 141 Ohio St.3d 375, 2014-Ohio-4270, 24 N.E.3d 1132, in asserting his entitlement to the writ. There, the parole board had denied prisoner Bernard Keith's request for parole, explaining that its decision was based in part on information in his parole-board file indicating that he had been paroled eight times. Id. at ¶ 6. That information was incorrect; Keith had been paroled six times. Id. at ¶ 12. We granted a writ of mandamus, concluding that because Keith had "made a showing that there may be substantive errors in his record," the APA "must therefore conduct an investigation into Keith's allegations and correct any substantive errors" in his parole-board file. (Emphasis added.) Id. at ¶ 30.
{¶ 8} We did not define "substantive error" in Keith , but Black's Law Dictionary explains that "substantive error" is synonymous with "substantial error," Black's Law Dictionary 660 (10th Ed.2014). It is "[a]n error that affects a party's substantive rights or the outcome of the case" and, as a consequence, "may require reversal on appeal." Id.2 It was clear in Keith that the alleged error was substantive-that it could have affected the parole board's consideration of Keith's parole-because the parole board had expressly based its decision in part on the erroneous information. See Keith at ¶ 6.
{¶ 9} Thus, we review each of the five alleged errors asserted by Cobb to determine whether there is a reasonable possibility that but for the alleged error, the parole board would have reached a different decision.
The assault allegations
{¶ 10} The first alleged error raised by Cobb concerns a factual narrative of his crimes contained in the Parole Board Information Sheet that was apparently derived from witness statements. Specifically, Cobb disputes the narrative's *530accuracy in stating that before robbing and shooting the victim, Cobb and another person assaulted the victim "with the butt of a gun, their fists, and their feet." Cobb claims that the information about the assault is inconsistent with the victim's autopsy report, which does not refer to any *1195external injuries beyond the gunshot wound. Because Cobb pleaded guilty to the robbery and murder offenses, the factual record before us is minimal.
{¶ 11} But even accepting Cobb's characterization of the record, we conclude that he has not alleged a substantive inaccuracy sufficient to warrant a writ of mandamus. This is because the parole board did not base its determination that Cobb's release would demean "the serious nature of the crime," Ohio Adm.Code 5120:1-1-07(A)(2), on the assault allegations. Rather, the parole board was explicit that its finding on seriousness was predicated on the victim's having been shot in the back and then robbed: "The Board by way of a Majority Vote has determined that a release at this time would demean the serious nature of this crime. The male victim in this offense was shot in the back by the offender and was then robbed of his property that was on his person." Because it is clear that the allegedly inaccurate information about the assault had no bearing on the parole board's decision, Cobb has suffered no prejudice.
{¶ 12} In denying Cobb's claim based on the disputed assault allegations, the magistrate reasoned: "The information sheet [Cobb] attached is not mentioned in the parole board's decision to deny him parole and [he] cannot establish that it was even considered." 2017-Ohio-1170, 2017 WL 1180653, ¶ 57. Cobb is correct that this analysis misapplies our holding in Keith , 141 Ohio St.3d 375, 2014-Ohio-4270, 24 N.E.3d 1132. Under the magistrate's approach, an inmate would have a viable Keith claim only if the parole board had expressly cited the allegedly false information in its decision. This is inconsistent with our recent conclusion that "a writ will issue when there is a credible claim of an error that may prevent the inmate's application from receiving meaningful consideration," State ex rel. Keith v. Dept. of Rehab. & Corr. , 153 Ohio St.3d 568, 2018-Ohio-3128, 109 N.E.3d 1171 (" Keith II "), ¶ 16, citing Keith at ¶ 21, 30. Thus, we do not hold that an inmate can never establish a meritorious Keith claim unless the alleged error is specifically referred to in the parole board's decision.
{¶ 13} The question is whether the alleged error, supported by evidence, may have affected the outcome of the parole hearing. See Keith at ¶ 28, 30. Because it is apparent here that the parole board did not rely on the alleged inaccuracy in analyzing the Ohio Adm.Code 5120:1-1-07(A) factors and reaching its decision, Cobb has not made a credible allegation of a substantive error. Thus, we deny Cobb's claim for relief based on the assault allegations.
The description of Cobb's sentence
{¶ 14} Cobb next alleges that two records in the parole board's hearing file-the Parole Board Information Sheet and the minutes of his 2014 clemency *531hearing-incorrectly state his aggregate prison sentence to be 23 years to life instead of 18 years to life. Cobb's sentence is clearly 18 years to life: he received a sentence of 15 years to life on the murder count, to be served consecutively to a 3-year sentence for the gun specification, for an aggregate minimum sentence of 18 years. The trial court also imposed a concurrent 5-year sentence for the robbery conviction.
{¶ 15} Cobb argues that his aggregate sentence is notated in a manner suggesting that the 5-year term was imposed consecutively instead of concurrently: "3.00 GUN + 5.00 TERM + 15.00-LIFE" (capitalization sic) on the Parole Board Information Sheet and "3 Gun + 5 Term + 15 - Life" in the clemency-hearing minutes. But the concurrent nature of the 5-year term is reflected in the Parole Board Decision and Minutes: "15-life + 3 gun cc/w/ 5 years"
*1196(or, in other words, concurrent with 5 years). And there is no doubt that the parole board understood that Cobb's minimum sentence is 18 years-because he was given a parole hearing in 2015, near the end of his 18th year of incarceration.3 When a sentence of life imprisonment is imposed for the offense of murder, a prisoner becomes eligible for parole "at the expiration of the prisoner's minimum term." R.C. 2967.13(A)(1). If the APA had incorrectly believed that Cobb's sentence was 23 years to life, as Cobb suggests, then his first parole hearing would not have been held until 2020. Thus, we conclude that Cobb has failed to demonstrate any error based on the description of his aggregate sentence.
Problematic conduct
{¶ 16} Cobb next takes issue with the board's determination that he had engaged in "problematic conduct" during his time as an inmate. He disputes the board's finding based largely on his assertion that one of the board members commended him at the hearing for his "good institutional behavior and growth." Cobb has presented two pieces of evidence to establish his good behavior: his Ohio Department of Rehabilitation and Correction "Job History" sheet, which indicates that he had not been placed in the prison's "bad behavior" housing unit in the past ten years; and a document detailing his security-classification level, which had been lowered to the least restrictive level three years prior to the hearing.
{¶ 17} Cobb essentially asks us to consider the reasonableness of the board's concern over problematic conduct, but he has not pointed to a specific error in the materials that the parole board relied on. In its decision, the board encouraged Cobb to "work on not receiving any future conduct reports." Although the *532documents he cites demonstrate some good conduct in recent years, he has not made a showing that there were no instances of bad conduct in his parole-board file on which the board could have based its determination. Thus, he has failed to present credible evidence of a substantive inaccuracy in the information in the parole board's file concerning his behavior in prison.
Alleged statements of parole-board members
{¶ 18} The last two errors claimed by Cobb are premised solely on statements allegedly made by board members at his parole hearing. The first pertains to a board member's alleged statement asking Cobb "to elaborate on his juvenile felonious assault conviction," even though that charge had been dismissed. The second involves a board member's alleged statement that Cobb had been transferred from another institution in 2004 for "failure to adjust," whereas Cobb maintains he was transferred for a different reason.
{¶ 19} The question is whether either of the purported statements constitutes a credible allegation of error in Cobb's parole-board file sufficient to trigger the parole board's duty to review his file. In both instances, we think they do not. It is equally plausible that the parole-board members misread an accurate record of Cobb's juvenile history and misstated the basis for Cobb's transfer to another institution. We decline to create a rule in which an inmate's unsubstantiated allegation of an incorrect statement made during a parole hearing, by itself, presents a claim of error in his parole-board file sufficient to entitle him to a writ of mandamus. Thus, we deny Cobb's request for relief based on the alleged statements regarding *1197the juvenile charge and the basis for his prison transfer.
Conclusion
{¶ 20} For the reasons stated above, we affirm the judgment of the court of appeals denying the requested writ of mandamus.
Judgment affirmed.
O'Connor, C.J., and O'Donnell, J., concur.
Kennedy, J., concurs in judgment only.
Fischer, J., concurs in part and dissents in part, with an opinion joined by French, J.
DeGenaro, J., not participating.
Because the APA's motion to dismiss contained matters outside the record, the magistrate treated it as a motion for summary judgment. See Civ.R. 12(B).
The separate opinion challenges this standard, asserting that Keith requires a showing not of a substantive error but only of the possibility of a "significant" or "nontrivial" error, without any consideration of whether the possible error may have affected the outcome. Opinion concurring in part and dissenting in part at ¶ 23. It says that in our multiple references in Keith to "substantive error," we were simply praising Keith for "going above and beyond" what was required. Id. at ¶27. But, after Keith , in an opinion joined by the author of today's separate opinion, this court reiterated our holding in Keith as "requiring 'a showing that there may be substantive errors in [the inmate's] record that may influence the [APA's] consideration of his parole.' " (Brackets sic.) Keith v. Dept. of Rehab & Corr. , 153 Ohio St.3d 568, 2018-Ohio-3128, 109 N.E.3d 1171, ¶ 16, quoting Keith at ¶ 30.
Cobb received 173 days of pretrial credit at the time of his sentencing on January 27, 1998, indicating that his incarceration began in August 1997. He became eligible for parole 18 years later in 2015, as indicated throughout the parole-board records.