Equifax (EFX) could be a solid choice for investors given the company's remarkably improving earnings outlook. While the stock has been a strong performer lately, this trend might continue since analysts are still raising their earnings estimates for the company.The upward trend in estimate revisions for this credit reporting company reflects growing optimism of analysts on its earnings prospects, 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 -- is principally built on this insight.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 Equifax, there has been strong agreement among the covering analysts in raising earnings estimates, which has helped push consensus estimates considerably higher for the next quarter and full year.The chart below shows the evolution of forward 12-month Zacks Consensus EPS estimate:12 Month EPSCurrent-Quarter Estimate RevisionsThe company is expected to earn $1.68 per share for the current quarter, which represents a year-over-year change of +5%.Over the last 30 days, the Zacks Consensus Estimate for Equifax has increased 13.79% because seven estimates have moved higher compared to no negative revisions.Current-Year Estimate RevisionsFor the full year, the earnings estimate of $6.95 per share represents a change of -0.29% from the year-ago number.The revisions trend for the current year also appears quite promising for Equifax, with nine estimates moving higher over the past month compared to no negative revisions. The consensus estimate has also received a boost over this time frame, increasing 10.02%.Favorable Zacks RankThanks to promising estimate revisions, Equifax currently carries a Zacks Rank #2 (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 LineEquifax shares have added 27.9% over the past four weeks, suggesting that investors are betting on its impressive estimate revisions. So, you may consider adding it to your portfolio right away to benefit from its earnings growth prospects.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 Equifax, Inc. (EFX): Free Stock Analysis Report To read this article on Zacks.com click here. Zacks Investment Research