Caterpillar (NYSE:CAT), the world's largest manufacturer of heavy mining equipment, has fallen out of favor with investors. The stock is down nearly 20% over the last six months -- no surprise, as the company itself has noted that its business abroad isn't likely to rebound much, if at all, during 2015. However, a beat in quarterly earnings estimates when Caterpillar announces its fourth-quarter results Tuesday could be just what the doctor ordered for its struggling stock price. Here's a look at Caterpillar's recent retail statistics and what analysts expect in the new report.

December retail
Caterpillar's machine retail sales break down into two categories: construction industries and resource industries. The following charts show Caterpillar's global retail statistics for three-month rolling averages, year over year.

Graph by author. Data source: Caterpillar.

As you can see, despite sales moving in the right direction, year-over-year comparisons remain negative. Resource industries was once Caterpillar's bread-and-butter business segment, and generated significantly more operating profit than its other business segments as recently as 2012.

Graph by author. Data source: Caterpillar.

Caterpillar's resource industries' sales in December did not impress investors, and the company's construction industries' results are also trending the wrong way.

Graph by author. Data source: Caterpillar.

As this chart shows, Caterpillar's construction industries sales have completely reversed over the last year. When combining the resource industries and construction industries segments, Caterpillar's global machine retail sales checked in 12% lower for the three-month rolling period ending in December, compared to last year. That is worse than November's decline of 10% and October's 9% slide.

Investors can expect the sales decline to negatively impact Caterpillar's quarterly results, but there should be a bright spot on Tuesday: energy and transportation. This is the one Caterpillar business segment that is growing at a rapid clip.

Graph by author. Data source: Caterpillar.

What to watch
Analysts expect Caterpillar to report earnings per share of $1.55 for the quarter and $6.55 for the full year, according to Forbes. There are a few additional things for investors to keep an eye on.

During Caterpillar's conference call on Tuesday, investors should listen for how negatively management believes the drop in oil prices will impact its energy and transportation segment, which provides engine products, generators, and oil and gas transportation applications, among other products. It will be a huge setback if management believes the recent growth in this segment will fade through 2015.

On the flip side, it will be a pleasant surprise if Caterpillar's energy and transportation business segment can offset the revenue decline in construction industries and continued weakness in resource industries. However, analysts don't expect that to happen, and predict revenue in the fourth quarter to decline by 2%.

Nonetheless, Caterpillar has done a solid job of cutting costs to improve profitability. According to Forbes, Caterpillar's last four quarters have averaged a 14% increase in year-over-year profit.

Beating earnings estimates on Tuesday would provide some short-term relief in Caterpillar's beaten-down stock price, but it will still be a rough 2015 for investors looking for a quick and more stable rebound in its global business.