Here at Zacks, our focus is on the proven Zacks Rank system, which emphasizes earnings estimates and estimate revisions to find great stocks. Nevertheless, we are always paying attention to the latest value, growth, and momentum trends to underscore strong picks.Of these, value investing is easily one of the most popular ways to find great stocks in any market environment. Value investors use a variety of methods, including tried-and-true valuation metrics, to find these stocks.Zacks has developed the innovative Style Scores system to highlight stocks with specific traits. For example, value investors will be interested in stocks with great grades in the "Value" category. When paired with a high Zacks Rank, "A" grades in the Value category are among the strongest value stocks on the market today.One stock to keep an eye on is Kroger (KR). KR is currently sporting a Zacks Rank of #1 (Strong Buy) and an A for Value. The stock holds a P/E ratio of 11.95, while its industry has an average P/E of 21. Over the past 52 weeks, KR's Forward P/E has been as high as 15.17 and as low as 9.88, with a median of 12.66.We also note that KR holds a PEG ratio of 1.34. This metric is used similarly to the famous P/E ratio, but the PEG ratio also takes into account the stock's expected earnings growth rate. KR's PEG compares to its industry's average PEG of 3.38. Over the last 12 months, KR's PEG has been as high as 2.26 and as low as 1.32, with a median of 1.85.Investors should also recognize that KR has a P/B ratio of 3.17. The P/B is a method of comparing a stock's market value to its book value, which is defined as total assets minus total liabilities. KR's current P/B looks attractive when compared to its industry's average P/B of 3.95. Over the past 12 months, KR's P/B has been as high as 3.82 and as low as 2.36, with a median of 2.98.Value investors also use the P/S ratio. The P/S ratio is is calculated as price divided by sales. This is a prefered metric because revenue can't really be manipulated, so sales are often a truer performance indicator. KR has a P/S ratio of 0.22. This compares to its industry's average P/S of 0.3.Finally, we should also recognize that KR has a P/CF ratio of 6.46. This metric takes into account a company's operating cash flow and can be used to find stocks that are undervalued based on their solid cash outlook. KR's P/CF compares to its industry's average P/CF of 13.46. Over the past year, KR's P/CF has been as high as 7.77 and as low as 3.49, with a median of 4.80.These figures are just a handful of the metrics value investors tend to look at, but they help show that Kroger is likely being undervalued right now. Considering this, as well as the strength of its earnings outlook, KR feels like a great value stock at the moment. Infrastructure Stock Boom to Sweep America A massive push to rebuild the crumbling U.S. infrastructure will soon be underway. It’s bipartisan, urgent, and inevitable. Trillions will be spent. Fortunes will be made. The only question is “Will you get into the right stocks early when their growth potential is greatest?” Zacks has released a Special Report to help you do just that, and today it’s free. Discover 7 special companies that look to gain the most from construction and repair to roads, bridges, and buildings, plus cargo hauling and energy transformation on an almost unimaginable scale.Download FREE: How to Profit from Trillions on Spending for Infrastructure >>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 The Kroger Co. (KR): Free Stock Analysis Report To read this article on Zacks.com click here. Zacks Investment Research