This research investigates whether the effect of low- versus high-variance product reviews on the evaluation of a product about which consumers have favorable or unfavorable prior expectation can vary depending on product type, the argument quality of product reviews, and the number of reviewers. The data across three laboratory experiments demonstrate that high-variance product reviews are more likely than low-variance product reviews to undermine product evaluation when consumers have unfavorable prior expectation about a product. When consumers have favorable prior expectation, however, high-variance product reviews can enhance or undermine product evaluation depending on product category, the argument quality of reviews, and the number of reviewers. The findings are explained by the type of causal attribution consumers make, such that high-variance product reviews can allow consumers to make biased product evaluation consistent with their prior expectation when the causes of variance in the product reviews are attributed to the reviewers rather than to the product. However, when the causes of variance are attributed to the product rather than the reviewers, high-variance product reviews can undermine product evaluation regardless of the favorability of prior expectation.