Plaintiff MELISSA LYNN STANLEY represented by DANIEL W. EMERY, LEAD ATTORNEY ATTORNEY TO BE NOTICED
Defendant SOCIAL SECURITY ADMINISTRATION, COMMISSIONER represented by JEANNE D. SEMIVA SOCIAL SECURITY ADMINISTRATION OFFICE OF GENERAL COUNSEL, JOHN F. KENNEDY FEDERAL, LEAD ATTORNEY, ATTORNEY TO BE NOTICED, NATASHA OELTJEN, SOCIAL SECURITY, ADMINISTRATION, OFFICE OF GENERAL COUNSEL, REGION I, ATTORNEY TO BE NOTICED
REPORT AND RECOMMENDED DECISION 
John H. Rich III United States Magistrate Judge
This Supplemental Security Income (“SSI”) appeal raises the question of whether the administrative law judge supportably found the plaintiff capable of performing work existing in significant numbers in the national economy. The plaintiff seeks reversal and remand on the bases that the administrative law judge’s mental residual functional capacity (“RFC”) determination was inadequate on its face and unsupported by any medical opinion of record. See Itemized Statement of Errors Pursuant to Local Rule 16.3 Submitted by Plaintiff (“Statement of Errors”) (ECF No. 10) at 2-4. I find no reversible error and, accordingly, recommend that the court affirm the decision.
Pursuant to the commissioner’s sequential evaluation process, 20 C.F.R. § 416.920; Goodermote v. Secretary of Health & Human Servs., 690 F.2d 5, 6 (1st Cir. 1982), the administrative law judge found, in relevant part, that the plaintiff had severe impairments of major depressive disorder, post-traumatic stress disorder (“PTSD”), and personality disorder, Finding 2, Record at 20; that she retained the RFC to perform a full range of work at all exertional levels, with a nonexertional limitation to unskilled work, Finding 4, id. at 22; that considering her age (25 years old, defined as a younger individual, on October 7, 2009, the date that she filed her application), education (limited), work experience (transferability of skills immaterial), and RFC, there were jobs existing in significant numbers in the national economy that she could perform, Findings 6-9, id. at 26; and that she, therefore, had not been disabled since October 7, 2009, the date that her application was filed, Finding 10, id. at 27. The Appeals Council declined to review the decision, id. at 1-3, making the decision the final determination of the commissioner, 20 C.F.R. § 416.1481; Dupuis v. Secretary of Health & Human Servs., 869 F.2d 622, 623 (1st Cir. 1989).
The standard of review of the commissioner’s decision is whether the determination made is supported by substantial evidence. 42 U.S.C. § 1383(c)(3); Manso-Pizarro v. Secretary of Health & Human Servs., 76 F.3d 15, 16 (1st Cir. 1996). In other words, the determination must be supported by such relevant evidence as a reasonable mind might accept as adequate to support the conclusion drawn. Richardson v. Perales, 402 U.S. 389, 401 (1971); Rodriguez v. Secretary of Health & Human Servs., 647 F.2d 218, 222 (1st Cir. 1981).
The administrative law judge reached Step 5 of the sequential evaluation process, at which stage the burden of proof shifts to the commissioner to show that a claimant can perform work other than her past relevant work. 20 C.F.R. § 416.920(g); Bowen v. Yuckert, 482 U.S. 137, 146 n.5 (1987); Goodermote, 690 F.2d at 7. The record must contain substantial evidence in support of the commissioner’s findings regarding the plaintiff’s RFC to perform such other work. Rosado v. Secretary of Health & Human Servs., 807 F.2d 292, 294 (1st Cir. 1986).
The plaintiff presses two related points: that the administrative law judge erred in crafting a mental RFC determination that is (i) inadequate on its face, given that whether a claimant can perform unskilled work is a function of skill level, not mental impairment, and (ii) unsupported by any medical opinion of record. See Statement of Errors at 2-4.
The commissioner concedes that this court has held that an administrative law judge may not assume, without explaining, that moderate limitations in concentration, persistence, or pace can be accommodated by a limitation to simple work alone, and that it is well-established that an administrative law judge may not base an RFC assessment on his or her own lay interpretation of medical data or substitute his or her judgment for that of medical experts. See Defendant’s Opposition to Plaintiff’s Itemized Statement of Errors (“Opposition”) (ECF No. 14) at 3.
Nonetheless, she correctly notes that this court has also held that either error is harmless if there is no medical opinion of record identifying greater limitations than those included in the RFC assessment. See id. at 3-4 (citing Veach v. Commissioner of Soc. Sec. Admin., Civil No. 1:13-CV-76-DBH, 2014 WL 35362, at *4 (D. Me. Jan. 6, 2014), Gonsalves v. Astrue, Civil No. 09-181-BW, 2010 WL 1935753, at *6 (D. Me. May 10, 2010) (rec. dec., aff’d June 16, 2010), and MacFarlane v. Astrue, No. 07-132-P-H, 2008 WL 660225, at *4 (D. Me. Mar. 5, 2008) (rec. dec., aff’d Apr. 1, 2008)). She argues that that is the case here.
The record contains five expert opinions bearing on the plaintiff’s mental functioning: (i) a May 5, 2005, mental RFC assessment by Brenda Sawyer, Ph.D., see Record at 460, which the parties agree relates to an earlier disability application/time period and was not addressed in the decision at issue, see Statement of Errors at 3 n.1; Opposition at 4 n.1, (ii) a January 13, 2009, Psychiatric Review Technique Form (“PRTF”) by non examining consultant David R. Houston, Ph.D., finding insufficient evidence to assess the severity of the plaintiff’s mental impairments from January 1, 2007, through the date of the evaluation, see Record at 585-97, which the commissioner notes bears on an earlier disability application/time period and was not addressed in the decision at issue, see Opposition at 4 n.1, (iii) a January 29, 2010, PRTF by non examining consultant Lewis F. Lester, Ph.D., finding insufficient evidence to assess the severity of the plaintiff’s mental impairments from September 18, 2008, through the date of the evaluation, see Record at 379-91, (iv) a report dated August 27, 2010, by examining consultant Donald Devine, Ph.D., see Id . at 443-45, and (v) a September 1, 2010, PRTF by non examining consultant Brian Stahl, Ph.D., finding non severe impairments of a personality disorder and a substance addiction disorder, with insufficient evidence of restriction of activities of daily living, mild difficulties in maintaining social functioning, mild difficulties in maintaining concentration, persistence, or pace, and no episodes of decompensation, see id. at 447-59.
No treating source provided an RFC opinion, and no medical expert testified at hearing.
The plaintiff relies on the Devine report, which she contends the administrative law judge mischaracterized as reflecting only mild difficulties in memory and concentration. See Statement of Errors at 3-4. At oral argument, her counsel also pointed to Global Assessment of Functioning (“GAF”) scores of 40 and 42, indicative of serious impairment, and argued that it was a stretch for the commissioner to speculate that any expert RFC opinion would ...