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.Considering these trends, value investing is clearly one of the most preferred ways to find strong stocks in any type of market. Value investors use a variety of methods, including tried-and-true valuation metrics, to find these stocks.Luckily, Zacks has developed its own Style Scores system in an effort to find stocks with specific traits. Value investors will be interested in the system's "Value" category. Stocks with both "A" grades in the Value category and high Zacks Ranks are among the strongest value stocks on the market right now.One company value investors might notice is Select Medical (SEM). SEM is currently sporting a Zacks Rank of #2 (Buy), as well as an A grade for Value. The stock has a Forward P/E ratio of 14.72. This compares to its industry's average Forward P/E of 18.81. Over the past year, SEM's Forward P/E has been as high as 20.21 and as low as 11.59, with a median of 14.95.SEM is also sporting a PEG ratio of 0.98. This popular metric is similar to the widely-known P/E ratio, with the difference being that the PEG ratio also takes into account the company's expected earnings growth rate. SEM's PEG compares to its industry's average PEG of 1.45. SEM's PEG has been as high as 1.35 and as low as 0.77, with a median of 1, all within the past year.We should also highlight that SEM has a P/B ratio of 4.03. 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. This stock's P/B looks attractive against its industry's average P/B of 4.08. Over the past 12 months, SEM's P/B has been as high as 4.30 and as low as 1.58, with a median of 2.94.Finally, our model also underscores that SEM has a P/CF ratio of 10.07. This data point considers a firm's operating cash flow and is frequently used to find companies that are undervalued when considering their solid cash outlook. This company's current P/CF looks solid when compared to its industry's average P/CF of 16.40. Over the past 52 weeks, SEM's P/CF has been as high as 10.75 and as low as 4.65, with a median of 7.77.These are just a handful of the figures considered in Select Medical's great Value grade. Still, they help show that the stock is likely being undervalued at the moment. Add this to the strength of its earnings outlook, and we can clearly see that SEM is an impressive value stock right now. Breakout Biotech Stocks with Triple-Digit Profit Potential The biotech sector is projected to surge beyond $775 billion by 2024 as scientists develop treatments for thousands of diseases. They’re also finding ways to edit the human genome to literally erase our vulnerability to these diseases. Zacks has just released Century of Biology: 7 Biotech Stocks to Buy Right Now to help investors profit from 7 stocks poised for outperformance. Our recent biotech recommendations have produced gains of +50%, +83% and +164% in as little as 2 months. The stocks in this report could perform even better.See these 7 breakthrough stocks now>>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 Select Medical Holdings Corporation (SEM): Free Stock Analysis Report To read this article on Zacks.com click here. Zacks Investment Research