Memorandum on Rating Threshold Rule
A person has established a private rule governing the minimum rating required before they will purchase a product they have already decided to purchase.
Memorandum on Rating Threshold Rule Counterfactual Analysis of Purchase Decision Support Behavior
The Rule
The person will not purchase a product with fewer than four stars. Products with exactly four stars are evaluated case by case. Products with 4.2 stars or higher are considered acceptable pending review of the review count. A product with a 4.7 average based on eleven reviews is treated with more skepticism than a product with a 4.3 average based on 2,400 reviews.
The rule has not been written down prior to this document. It has been applied consistently for approximately three years.
What Would Have Happened Without the Rule
Without the rating threshold rule, the person would have purchased the same products they purchased with the rule, because the rule did not change the destination, only the path to it. The products selected after threshold review are the products the person identified before threshold review.
The rule is consulted after the product has been identified, not before.
Consequence One
The rule provides a rejection mechanism that the person uses rarely. It has prevented approximately four purchases in three years, all of which were replaced by functionally identical products with higher review counts. Whether those products were superior is not known and has not been examined.
Consequence Two
The rule generates a secondary research behavior. When a product meets the threshold, the person reads the one-star reviews to determine whether the negative experiences reflect a systemic problem or a user error. This investigation takes between seven and twenty minutes. The investigation has changed a purchase decision twice.
The rest of the time it confirms a decision already made.
Consequence Three
The person has purchased products from categories where the review system is known to be compromised by incentivized reviews. The threshold is applied to these categories using the same criteria as uncompromised categories. The threshold serves as a formality that allows the person to feel they conducted due diligence before doing what they intended to do from the beginning.
The Rule, Evaluated
The rule is consistently applied and consistently insufficient as a substitute for actual product evaluation. It screens for catastrophic failure at a category level. It does not distinguish between products within a quality band. A product with a 4.4 and a product with a 4.6 occupy the same functional category under the rule, which is the category of acceptable.
Both are purchased with equal confidence. The confidence is not warranted by the data.
The Contradiction
The rating threshold rule is designed to reduce uncertainty in purchase decisions. Reducing uncertainty is valuable. The rule does reduce uncertainty, but it reduces a type of uncertainty the person was not actually anxious about, which is whether the product is a complete failure. The uncertainty the person experiences is about whether the product is the right choice among adequate options.
The rule does not address the experienced uncertainty. It addresses an adjacent uncertainty with professional indifference to the distinction.