NEW YORK — Thanksgiving could be the best day to shop all year.

An analysis of sales data and store circulars by two research firms contradicts conventional wisdom that Black Friday is when shoppers can get the most and biggest sales of the year.

Turns out, shoppers will find more discounted items in stores that are open on Thanksgiving. For example, there are a total of 86 laptops and tablets deeply discounted as door buster deals at Best Buy, Walmart and others on the holiday compared with just nine on Black Friday, according to an analysis of promotions by researcher Market Track.

And on the Web, discounts will be deeper on the holiday. Online prices on Thanksgiving are expected to be about 24 percent cheaper compared with 23 percent on Black Friday and 20 percent on Cyber Monday, according to Adobe, which tracks data on 4,500 retail websites.

The data is the latest proof that retailers are slowly redefining the Black Friday tradition. It’s been the biggest shopping day of the year for decades, mostly because it’s traditionally when retailers pull out their best sales events. But in the last few years, retailers like the Gap, Target and Toys R Us have started opening their stores and offering holiday discounts on Thanksgiving to better compete with online rivals.

“I was surprised, but it really shifted one day,” said Tamara Gaffney, principal analyst at Adobe.

Shoppers already are noticing the deals on Thanksgiving. Corey Grassell, 34, of Appleton, Wisc., said he plans to shop for deals on Thanksgiving and bypass Black Friday. That’s after he grabbed bargains last year on the holiday, including a washer-dryer combination at Sears for about $800, a 50 percent discount.