Social Proof and Reviews: How They Lift Online Conversion

Social proof, meaning reviews, ratings, customer photos and visible popularity, lifts conversion because it reduces the risk a shopper feels before buying. Northwestern University's Spiegel Research Center found that the purchase likelihood for a product with five reviews was 270% greater than for a product with no reviews. The biggest gains come from the first handful of genuine reviews, so collecting them systematically, and never faking them, is one of the cheapest conversion improvements a retailer can make.

What the research shows

The Spiegel study, run with ratings platform PowerReviews, analysed millions of customer interactions across three online retailers. Its main findings remain the most cited evidence on reviews and sales:

• The first reviews matter most. Purchase likelihood rose sharply as products went from zero to five reviews, with the first five reviews driving the bulk of the increase.
• Reviews matter more for expensive items. At the gift retailer studied, displaying reviews lifted conversion 190% for a lower-priced product and 380% for a higher-priced product. More risk means more reliance on other buyers.
• Verified buyers carry weight. Reviews from verified buyers tended to be more positive than anonymous ones, and purchase likelihood increased 15% when shoppers saw reviews from verified buyers rather than anonymous reviewers.

The study is from 2017 and US-based, so treat the percentages as directional. The practical lesson still applies: a few credible reviews give shoppers more confidence than a polished product page with none.

Social proof on social media

Reviews no longer live only on product pages. DHL's 2025 Australian survey found 60% of Australian shoppers say customer reviews on social media influence their buying decisions, and 71% say trends or viral products influence them.

That means social proof now includes:

• comments and replies under your posts
• customer photos and videos tagged with your brand
• creator reviews and unboxings (covered in influencer and UGC marketing)
• star ratings shown in marketplace listings that shoppers screenshot and share

Reviews also feed AI shopping tools. Bazaarvoice's 2025 Shopper Experience Index, which surveyed consumers in six countries including Australia, cites research finding products with both high ratings and high review volumes get the strongest preference boost from AI agents. The same survey found 55% of consumers trust generative AI tools for at least some things.

The rules on reviews in Australia

The ACCC is clear: it is against the law for a business to create fake or misleading reviews or to arrange for others to do so. Reviews can mislead if they are written by family, staff or paid parties without disclosing the connection, or written by people who never used the product. The Australian Government's business.gov.au guidance adds that the ACCC considers a review fake or misleading if it is removed or changed by the business after the customer posts it, or comes from an incentive to write a positive review.

The ACCC has been actively monitoring this. Its 2023 update covered internet sweeps of both influencers and online reviews, with a stated focus on guidelines followed by enforcement.

Safe practices:

1. Ask every genuine customer for a review, not only the happy ones.
2. Do not suppress or delete negative reviews simply because they are negative.
3. If you offer an incentive, offer it for both positive and negative reviews and clearly disclose it.
4. Respond to criticism publicly and factually.

How to collect more genuine reviews

1. Ask at the right moment. Send a review request after delivery, timed to when the customer has used the product, not at dispatch.
2. Make it easy. One tap to a star rating, with optional text and photo upload.
3. Prioritise products with zero reviews. Given the Spiegel findings, getting new or slow-moving products to five reviews is worth more than adding a fiftieth review to a bestseller.
4. Use marketplace programs where they exist. Many marketplaces have their own review request tools and rules; follow them exactly.
5. Show reviews where decisions happen. Display ratings near price and add-to-cart, and reuse good review quotes (with permission) in social posts.
6. Fix what reviews tell you. Repeated complaints about sizing or a missing detail often point to a listing problem, which also reduces returns.

Key figures

• Products with five reviews were 270% more likely to be purchased than products with none (Spiegel Research Center, 2017).
• Displaying reviews lifted conversion 380% for a higher-priced product versus 190% for a lower-priced one (Spiegel Research Center, 2017).
• 60% of Australian shoppers say customer reviews on social media influence their purchases (DHL, 2025).
• Products with high ratings and high review volumes get the strongest preference boost from AI agents (Bazaarvoice, 2025).

How eComChannels helps

Reviews do the most work when shoppers see them. AI social media outreach helps you turn genuine reviews and customer photos, used with permission, into social posts across Facebook, Instagram, TikTok, Pinterest and other networks, so social proof reaches people still deciding rather than sitting only on a product page. Your team approves every post.

Reviews also expose weak listings. When customers keep asking the same question or report the same surprise, AI listing optimisation lets you update the product record once and push clearer titles, attributes and descriptions to every marketplace in bulk, which can reduce the gap between expectation and product that leads to poor reviews and returns.

Book a demo or start a 30-day free trial to see it with your catalogue.

FAQ

How many reviews does a product need?

The Spiegel research found the first five reviews drive most of the conversion lift, so five genuine reviews per product is a sensible first target, especially for higher-priced items.

Can I offer a discount in exchange for a review?

Be careful. Any incentive must be disclosed, and it must not depend on the review being positive. Some marketplaces ban incentivised reviews entirely, so check each platform's rules before offering anything.

Should I delete negative reviews?

No, unless they breach the platform's rules, for example abusive or off-topic content. Selectively removing negative reviews can mislead shoppers. A calm, factual reply usually builds more trust than a perfect score.