TripAdvisor (TRIP -0.50%) is set to post its earnings results before the market opens on Feb. 15. The online travel-booking giant's last few quarterly reports hit with a thud as its turnaround plan fizzled. But shareholders are hoping this week's results can put an end to that disappointing trend.

Let's take a closer look at what investors can expect on Thursday.

Hotel booking trends

TripAdvisor entered 2017 predicting a return to robust growth in its core hotel business following a rare decline in the prior year. That optimistic forecast hasn't panned out. Instead, the segment shrank in the most recent quarter and has only expanded by 1% over the first nine months of the year. 

A couple checking in to a hotel.

Image source: Getty Images.

Even worse is the fact that management doesn't seem to have a good reading on why the business is underperforming these days. After results missed expectations in the second quarter, CEO Stephen Kaufer and his team suggested that the stampede toward vacation shopping on mobile devices was to blame.

That explanation made it seem like a temporary challenge of simply finding better ways to monetize healthy customer traffic. In the next quarterly report, though, TripAdvisor said the hotel segment was hurt by reduced advertising demand even as traffic improved.

For the fourth quarter, executives forecast only a slight uptick in click-based transaction revenue, which they said would lead to low single-digit sales growth for the hotel segment.

Other income

While returning to growth in the hotel business has been harder than expected, TripAdvisor is finding plenty of success in its "non-hotel" division. That segment includes bookings for attractions, restaurants, and vacation rentals, and it is the only reason why overall sales rose last quarter -- and why profitability held steady despite plunging earnings in hotel bookings.

TripAdvisor's non-hotel business last posted a 26% sales spike as adjusted profit margin jumped to 35% of sales from 15%. The good news is that the drivers behind this growth are clear and fall right within the company's control. As TripAdvisor adds to its portfolio of bookable attractions, for example, its highly engaged customer base responds by making more reservations. TripAdvisor believes this business could become a key contributor to overall results over time. It is on pace to account for about 25% sales this year, up from just 9% in 2014.

Outlook for 2018

In their first official forecast for fiscal 2017, issued about a year ago, Kaufer and his team said they believed they were "turning a corner" after the hotel business declined 6% in 2016. They pointed to three consecutive quarters of improving trends on click-based and transaction revenue as support for their prediction that sales would rise by double digits last year.

TripAdvisor's outlook for 2018 likely won't be as optimistic. Barring a surprise improvement in the fourth quarter, management might predict only modest growth in the hotel business given the weak results over the past year. That forecast would include a significant cost-cutting initiative, especially if advertising demand stays sluggish. In any case, it's likely TripAdvisor will have to make major tweaks to its turnaround plan if it's going to avoid its third straight year of flat or declining sales.