Amazon (NASDAQ:AMZN) has generally avoided giving out specific business numbers when it has no legal requirement to do so. For example, the company does not report how many Prime members it has, nor does it share data on sales of its various Alexa-enabled devices.

Instead the e-commerce giant releases vague but upbeat statements touting its accomplishments. That's what it did after its latest Prime Day summer sales event, saying, "This year, Prime Day was once again the largest shopping event in Amazon history with more than one million deals exclusively for Prime members. Over the two days of Prime Day, on July 15 and 16, sales surpassed the previous Black Friday and Cyber Monday combined."

That's clearly impressive, but the company does not share any significant hard numbers. To try and figure out more specific info on Prime Day,, an online coupons website, surveyed 1,801 U.S. shoppers about Amazon. The study revealed some interesting things about what might have actually happened during the retail giant's big summer sales event.

An Amazon tractor trailer.

Amazon has shown that it can drive consumer behavior. Image source: Amazon.

The truth about Prime Day

According to the survey respondents, almost 95% said they had made a purchase on in the past 12 months. Of that group of 1,702 purchasers, 42% said they'd shopped during Prime Day in 2018 and 44% said they'd shopped during the sale this year. Nearly three-quarters of those surveyed (74%) said they had a Prime membership, while 3.6% said they'd joined the paid service specifically because of Prime Day.

And while 3.6% may seem like a small percentage, it's impressive that Amazon can drive any new membership to a program that has reached near saturation levels in the company's home market. It is worth noting, however, that 5.5% of those Amazon shoppers did say they plan to cancel the service immediately (though saying it and doing it are two different things).

Prime Day has clearly succeeded in driving Prime members to shop. More than half (53.3%) of the Prime members surveyed said they shopped on the made-up sales holiday, up from 50.3% last year. Marc Mezzacca wrote in a post on that "42% of Amazon Prime members shopped because of interest in Prime Day sales" and "[22.3%] stated they shopped purely for Prime Day sales, while [20.8%] stated they needed something but were also interested in Prime Day sales."

Another 10.2% of respondents said they shopped on Prime Day only because they needed something. Those who did shop, however, were largely satisfied, as 57.3% of Prime members surveyed rated the deals as "good or excellent" while 31% found them "so-so," and only 4% called them "terrible."

Christmas in July

Prime Day is sort of silly -- it's a major sales event not tied to a holiday or gift-giving occasion -- but it clearly works. The company has taken two days in July, a time before back-to-school shopping that's roughly the halfway point to Christmas, and made it a must-shop event for tens of millions of people.

That's impressive, and it shows the power that the online retail giant has. Amazon has shown it can motivate consumers to buy during a time of the year when they traditionally have had little reason to open their wallets. That's something very few -- if any -- other U.S.-based retailers or e-commerce sites can pull off (Alibaba has done a variation of it in China with its Singles Day event), and it cements the company's position as the U.S. leader in its space.

Walmart or Target can have sales, maybe even sales that drive a portion of its audience to make purchases they may not have otherwise. Neither retailer can create an event as big as any traditional holiday that drives this level of sales activity and customer engagement.

This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis -- even one of our own -- helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.