Stitch Fix (NASDAQ:SFIX) investors will no doubt be paying attention when the personalized styling service reports fourth-quarter earnings after hours on Tuesday, Oct. 1.

Since its initial public offering in 2017, the stock has been one of the most volatile on the market, and it has a pattern of swinging by double digits following its quarterly earnings reports. In fact, following its last four reports, the stock moved by an average of 23.4%.

With shares beaten down on concerns about challenges from Amazon, a slowing economy, and the trade war, strong results could send the stock surging. Beyond the headline numbers, here's what to look for in Stitch Fix's fourth-quarter earnings report.

A Stitch Fix box resting on a doorstep

Image source: Stitch Fix.

1. Can it play across the pond?

The biggest change Stitch Fix made in the fourth quarter was its May launch in the U.K., the company's first foray into a foreign country. Stitch Fix chose that market first for a number of reasons. The British spend more online than Americans do as a percentage of their overall apparel spending. There's less competition in the U.K. with other personalized styling services, so Stitch Fix has a greater chance of differentiating itself from the market. And the densely populated country is better suited for e-commerce, as shorter distances make shipping and returns easier.

On the third-quarter earnings call, shortly after the U.K. launch, CEO Katrina Lake sounded optimistic about the launch, saying "it seems like there is a lot of excitement from the [British] market" for Stitch Fix's service. Look for commentary and updates on the U.K. business, as Stitch Fix's results there will likely inform the brand's ability to penetrate other international markets.

2. Where is revenue growth coming from?

Despite the fact that Stitch Fix surged following its last two earnings reports, the stock is actually trading near all-time lows today. The most closely watched metric from the company has been revenue growth, the best indicator of the company's ability to truly change how people shop for clothes. Strong revenue growth is also the best way to quell the criticism that online styling services like Stitch Fix are a fad that will ultimately prove unsustainable.

There's tension between investors and the company over where Stitch Fix's growth should come from. During some quarters, the company has reported solid revenue growth, but the stock still plunged because user growth didn't meet expectations.

With its model, Stitch Fix has two ways of growing revenue. It can add new customers, or it can coax existing customers into spending more money on the platform. The market would prefer that it add new customers, but, as management has argued, increasing revenue per customer also shows that the brand is building long-term equity with its client base.

Stitch Fix impressed the market in its last earnings report with 29.1% revenue growth to $408.9 million, but active client growth was relatively modest at 16.6% to reach 3.13 million. For the fourth quarter, the company called for revenue growth of 34% to 37%, to a range of $425 million to $435 million; this includes a boost from the U.K. launch.

Pay attention to the mix of revenue growth between new and existing clients in the upcoming report. Remember that the active client count should get a bump from the U.K. launch, but also that Stitch Fix's fourth quarter has been a seasonally slow one for customer growth.

3. How does 2020 guidance look?

The most influential number in the earnings report, however, will likely be the company's revenue guidance for fiscal 2020.

Stitch Fix's full-year 2019 guidance for revenue growth has improved significantly over the course of the year, rising from forecasts for revenue to rise between 20% and 25% to a revised estimate for growth between 28% and 29% -- a sign the company is executing effectively. If management calls for a similar growth rate in fiscal 2020, it would likely delight investors. But that guidance may ultimately depend on progress in its U.K. business, as well as in newer segments like Men's, Kids, and Plus.

While the company's revenue trends are arguably the most important area for investors to check on, investors will also want to keep an eye on guidance for adjusted EBITDA (earnings before interest, taxes, depreciation, and amortization), as the market always likes increasing profits.

This time a year ago, management forecast adjusted EBITDA of $20 million to $40 million for 2019, and the company is now targeting the high end of that range for the full year. With the investments to kick off the U.K. market now in the past, we could see a jump in adjusted EBITDA for 2020. Notably, Stitch Fix's expected 2019 adjusted EBITDA total is actually down from results of $53.6 million in 2018 and $60.6 million in 2017. So it would be encouraging to see guidance for an uptick in this metric in 2020.

With the stock in a rut, it shouldn't take much to deliver a pop -- especially since shares could also benefit from a short squeeze, since about a third of the float is sold short. If Stitch Fix can give the right answers to the questions above, look for the stock to soar on Wednesday.