(b) Quantification of damages
 We turn now to the issue of aggregate damages. Because
the courts below excluded the umbrella purchasers from the
class, they did not consider whether aggregate damages for the
class, when umbrella purchasers are included, could be certified
as a common issue. Counsel gave limited treatment to this issue
in their submissions. Based on our review of the statement of
claim and the expert reports, we are of the view that, once the
umbrella purchasers are included, aggregate damages for the
class cannot be certified as a common question. A subclass com-
posed of non-umbrella purchasers will have to be created for the
aggregate damage issue.
 In order for aggregate damages to be certified as a common
question, the appellants must establish that there is a “reasonable
likelihood” that the conditions required in s. 24 of the Class
Proceedings Act for determining aggregate damages would be
satisfied if the appellants are otherwise successful at the common
issues trial: Markson v. MBNA Canada Bank (2007), 85 O.R. (3d)
321,  O.J. No. 1684, 2007 ONCA 334, at para. 44; Fulawka
v. Bank of Nova Scotia (2012), 111 O.R. (3d) 346,  O.J. No.
2885, 2012 ONCA 443, at para. 111.
 Section 24 provides:
24(1) The court may determine the aggregate or a part of a defendant’s
liability to class members and give judgment accordingly where,
(a) monetary relief is claimed on behalf of some or all class members;
(b) no questions of fact or law other than those relating to the assessment
of monetary relief remain to be determined in order to establish the
amount of the defendant’s monetary liability; and
(c) the aggregate or a part of the defendant’s liability to some or all
class members can reasonably be determined without proof by
individual class members.
 Our concern is that both the statement of claim and Dr.
Reutter’s report appear to quantify the aggregate damages as
those that were suffered by the non-umbrella purchasers.
Further, neither address how aggregate damages for umbrella
purchasers could be quantified.
 As set out above, para. 76(c) of the statement of claim
pleads damages, namely, that all class members were harmed
because they paid more for LIBs and LIB products due to the
alleged conspiracy. However, the proposed quantification of those
damages is pleaded as follows, at para. 77:
The Plaintiffs assert that their damages, along with those of other members
of the proposed class, are capable of being quantified on an aggregate basis as