Saia (SAIA) appears an attractive pick given a noticeable improvement in the company's earnings outlook. The stock has been a strong performer lately, and the momentum might continue with analysts still raising their earnings estimates for the company.Analysts' growing optimism on the earnings prospects of this trucking company is driving estimates higher, which should get reflected in its stock price. After all, empirical research shows a strong correlation between trends in earnings estimate revisions and near-term stock price movements. Our stock rating tool -- the Zacks Rank -- has this insight at its core.The five-grade Zacks Rank system, which ranges from a Zacks Rank #1 (Strong Buy) to a Zacks Rank #5 (Strong Sell), has an impressive externally-audited track record of outperformance, with Zacks #1 Ranked stocks generating an average annual return of +25% since 2008.For Saia, strong agreement among the covering analysts in revising earnings estimates upward has resulted in meaningful improvement in consensus estimates for the next quarter and full year.Current-Quarter Estimate RevisionsThe earnings estimate of $2.55 per share for the current quarter represents a change of +68.87% from the number reported a year ago.The Zacks Consensus Estimate for Saia has increased 33.44% over the last 30 days, as six estimates have gone higher compared to no negative revisions.Current-Year Estimate RevisionsFor the full year, the earnings estimate of $9.22 per share represents a change of +77.31% from the year-ago number.There has been an encouraging trend in estimate revisions for the current year as well. Over the past month, five estimates have moved up for Saia versus no negative revisions. This has pushed the consensus estimate 12.61% higher.Favorable Zacks RankThanks to promising estimate revisions, Saia currently carries a Zacks Rank #1 (Strong Buy). The Zacks Rank is a tried-and-tested rating tool that helps investors effectively harness the power of earnings estimate revisions and make the right investment decision. You can see the complete list of today's Zacks #1 Rank (Strong Buy) stocks here.Our research shows that stocks with Zacks Rank #1 (Strong Buy) and 2 (Buy) significantly outperform the S&P 500.Bottom LineInvestors have been betting on Saia because of its solid estimate revisions, as evident from the stock's 37.2% gain over the past four weeks. As its earnings growth prospects might push the stock higher, you may consider adding it to your portfolio right away. Zacks’ Top Picks to Cash in on Artificial Intelligence This world-changing technology is projected to generate $100S of billions by 2025. From self-driving cars to consumer data analysis, people are relying on machines more than we ever have before. Now is the time to capitalize on the 4th Industrial Revolution. Zacks’ urgent special report reveals 6 AI picks investors need to know about today.See 6 Artificial Intelligence Stocks With Extreme Upside Potential>>Want the latest recommendations from Zacks Investment Research? Today, you can download 7 Best Stocks for the Next 30 Days. Click to get this free report Saia, Inc. (SAIA): Free Stock Analysis Report To read this article on Zacks.com click here. Zacks Investment Research