Investors interested in stocks from the Chemical - Diversified sector have probably already heard of Dow Inc. (DOW) and PPG Industries (PPG). But which of these two stocks is more attractive to value investors? We'll need to take a closer look to find out.We have found that the best way to discover great value opportunities is to pair a strong Zacks Rank with a great grade in the Value category of our Style Scores system. The Zacks Rank favors stocks with strong earnings estimate revision trends, and our Style Scores highlight companies with specific traits.Right now, Dow Inc. is sporting a Zacks Rank of #1 (Strong Buy), while PPG Industries has a Zacks Rank of #3 (Hold). The Zacks Rank favors stocks that have recently seen positive revisions to their earnings estimates, so investors should rest assured that DOW has an improving earnings outlook. But this is just one piece of the puzzle for value investors.Value investors are also interested in a number of tried-and-true valuation metrics that help show when a company is undervalued at its current share price levels.The Style Score Value grade factors in a variety of key fundamental metrics, including the popular P/E ratio, P/S ratio, earnings yield, cash flow per share, and a number of other key stats that are commonly used by value investors.DOW currently has a forward P/E ratio of 13.39, while PPG has a forward P/E of 21.88. We also note that DOW has a PEG ratio of 0.69. This figure is similar to the commonly-used P/E ratio, with the PEG ratio also factoring in a company's expected earnings growth rate. PPG currently has a PEG ratio of 1.19.Another notable valuation metric for DOW is its P/B ratio of 3.18. 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. By comparison, PPG has a P/B of 6.94.These are just a few of the metrics contributing to DOW's Value grade of B and PPG's Value grade of C.DOW stands above PPG thanks to its solid earnings outlook, and based on these valuation figures, we also feel that DOW is the superior value option right 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 Dow Inc. (DOW): Free Stock Analysis Report PPG Industries, Inc. (PPG): Free Stock Analysis Report To read this article on Zacks.com click here.