They have measurable, useful values. Investing is a different story. When a person invests in something, that person becomes an owner. For this ownership the investor receives a piece of paper. The value of that paper is its potential total return to investors.
People invest for total return-appreciation or dividends or some combination of the two.
When they invest for appreciation, investors look for the earnings potential of their investment. Today's Standard and Poor's 500 stock index is priced two and one half times more than investors have historically paid for earnings. In addition, many companies are valued at more than five times Standard and Poor's historical earnings multiple. To justify that pricing, those companies would need an annual earnings growth rate between the high teens and moderate double-digit numbers. Dividend yield is the total annual cash distribution an investor receives divided by the price paid by the investor.